Diet is Just A Four-Letter Word

By Stephen F. Barnes, Ph.D. San Diego State University

Diet is just a four-letter word. At any given time an estimated 75 million Americans are on some kind of formal diet or weight loss plan at an annual cost of $69 billion to them… and often frustrated with the slow progress they are making, feeling overweight, and suffering in silence. However, most of us are holding a “diet dance card,” that is, going through the physical and emotional motions of

worrying about our weight even if we are not currently out on the floor with the real fatties. It is estimated more than 70 percent of adults regularly consume reduced fat and other so-called “better for you” foods for weight management, and over half are making a concerted effort to reduce their calories or eat whole grain and fortified foods because they have been convinced such behaviors are really good for them. “Better for you” foods include diet, light, reduced cholesterol, reduced sodium, caffeine free, sugar free, fortified, organic, and low carb varieties. The average American, according to National Eating Trends, has at least two “better for you” products a day (NPD Group, 2008). Having said all of this, how’s that diet going? Not too well…? Happy with your current weight and body image? What, no comment…? The Diet Craze The history of human dieting is riddled with conjecture, bad science, and deception. In fact, there are so many claims and counter-claims today about what to eat or not eat, sandwiched between failed diets, it is a wonder the whole enterprise doesn’t simply implode. But instead it keeps growing at about 6 percent annually. It includes diet centers and programs, group and individual weight-loss plans, diet camps, prepackaged foods, over-the-counter and prescription diet drugs, weight-loss books and magazines, commercial and residential exercise clubs with weight-loss programs, sugar-free, fat-free, and reduced calorie ("lite") food products, imitation fats and sugar substitutes, and physicians, nurses, nutritionists, other health professionals specializing in weight-loss.

Key Concepts: Dieting Dieting is the intentional practice of regulating one’s food intake to achieve and maintain a desired weight threshold. Diets to promote weight loss, as opposed to those designed for weight gain, are often divided into one of the following types: low-carbohydrate, low-fat, low-calorie, and very low-calorie.

There can be little doubt America has been and remains preoccupied with diet, deprivation, and weight loss, as Susan Yager (2010) so ably chronicles in The Hundred Year Diet. And, it remains to be understood how one of the best-fed nations in the world developed some of the very worst eating habits. Diet fads have come and gone over the years, like rain. One of the earliest is attributed to William the Conqueror who became too fat to ride his horse. He devised an alcohol-only diet in 1087—which, of course, didn’t work. Another interesting approach to overindulgence was an 1829 diet consisting caffeine-free drinks, vegetarian cuisine, and the legendary graham cracker. Alas, today Presbyterian minister Sylvester Graham is only remembered for the graham cracker. Then in 1903 a self-taught nutritionist by the name of Horace Fletcher, dubbed “The Great Masticator,” proposed that people should chew their food exactly 32 times before spitting it out—an effective dieting strategy that, for obvious reasons, really didn’t catch on (Fletcher, 2009). Other ineffective fad diets have consisted of the first belt-driven fat massager developed in 1857 by Dr. Gustav Zander of Sweden, the invention of calorie counting in 1917, a cigarette diet pushed by several tobacco manufacturers in the 1920s that reportedly suppressed one’s appetite, a 1928 meat-and-fat diet based on the successful Intuit practice of eating primarily caribou, raw fish and whale blubber (with less than 2 percent of their diet coming from fruits, vegetables, and other carbs), the use of slimming soaps in the 1930s, a tapeworm diet in 1954 that was allegedly used by famous movie stars to keep the weight off, and Dr. Herman Taller’s 1961 “Calories Don’t Count” diet that permitted the unrestricted consumption of high protein, followed by ingesting three ounces of polyunsaturated vegetable oil in pill form (Wolf, 2005). Diet strategies currently making the rounds include gluten-free, 3 Day diet, and a Lemonade diet and variety of other cleansing programs that claim to remove toxins from your body. There is no serious scientific evidence behind any of these, of course. Here is some good advice for spotting fad diets. Be particularly cautious of any weight-loss plan that omits specific foods or food groups, identifies so-called “good” and “bad” foods, promises a quick fix, or is based on testimonials and/or little or no scientific research (WebMD, 2010a). Here is a brief thumbnail sketch of some of the more recent diets that have worked well for some people, actually resulting in weight loss (for a comprehensive diet survey see WebMD, 2010b):

Low-carbohydrate Diets • Atkins Diet, probably the most well-known and controversial low-carb diet, is based on the theory that overweight people eat more carbohydrates than they need for energy, with the unused portion being stored as body fat. By restricting carbohydrates to a mere fraction of that found in the typical American diet (less than 40 grams per day) the body enters a state known as ketosis, that is, it burns its own fat for fuel. Over time, the transition from weight loss to weight maintenance is made by gradually increasing carbs so long as gradual weight loss is maintained. Exercise in all phases of the diet is now emphasized.

In a meta-analysis of 107 studies of low-carbohydrate diets, Bravda et al. (2003) concluded that there currently was insufficient evidence to make recommendations

for or against the use of low-carbohydrate diets, particularly among participants older than age 50 years, for use longer than 90 days, or

for diets below 20 grams/day or less of carbohydrates. Among the published studies reviewed, weight loss

while using low-carbohydrate diets was principally associated with decreased caloric intake and

increased diet duration but not with reduced carbohydrate content.

Recent reviews of the Atkins diet have been more critical (Janicek, Willenberg, & Gabel, 2009).

Rapid weight loss in the first two weeks on these types of diets is due to diuretic water loss, not fat loss.

After the first two weeks the weight loss does continue, but only because of calorie restriction from the reduction of consumed carbohydrates. But there are some health consequences with ketosis: weakness, nausea, dehydration, light-headedness, irritability and a decrease in appetite. Prolonged ketosis may leach calcium out of the bones, increasing the risk of osteoporosis.

Key Concepts: Carbohydrates

The term carbohydrate, an organic compound, refers to any food rich in starch (e.g., bread, pasta, beans, potato, vegetables, rice) or sugar (e.g., fruit, soft drinks, candy). Carbohydrates are a major source of fuel for humans, necessary for physical and mental activity, and organ function. There are different types of carbohydrates that perform various complex functions in our bodies, ranging from energy storage to RNA production to immune system functionality. The liver breaks down the most digestible carbohydrates into glucose that then enters the blood stream and nourishes cells (Wikipedia, 2010; Harvard School of Public Health, 2010).

Because low carbohydrate diets are usually high in total fat, saturated fat, and cholesterol, the risk for developing heart disease and some forms of cancer may also be increased. Additionally, high protein intake, more than 35% of calories from protein consumption (e.g., in excess of 100 grams per day), puts enormous strain on the liver and kidneys, especially for people with diabetes who are already at risk for diabetic kidney disease. After the low-carb diet has ended, people often gain back the weight they previously lost. When carbohydrates are reintroduced into the diet, the body will store them as fat in response to the ketosis.

•South Beach Diet was invented by a cardiologist connected with at Mount Sinai Hospital in South Florida, hence the name. It was originally developed for overweight heart patients, but has spread across the country and has been a consistent New York Times Bestseller. It begins with a two-week induction phase in which most carbohydrates are avoided while meats, shellfish, chicken, turkey, fish, nuts, cheese (fat-free), eggs, salads, and vegetables are readily consumed. The result is an 8-10 pound weight loss similar to the Atkins Diet. In Phase Two some foods avoided in Phase One are re-introduced but according to a specific meal plan and recipes. Weight loss drops to 1-2 pounds per week. Phase Three is about living a sensible lifestyle, eating healthy foods, and balancing “good carbs against bad carbs” in order to maintain weight. The balancing is carried out on the basis of the Glycemic Index (see Key Concepts, below).

Key Concepts: Proteins

Proteins (aka polypeptides) are organic compounds made up of chains of 22 different amino acids. Proteins, via these amino acids, are fundamental components of all living cells and every cell requires protein in order to function properly. In humans, nine of these amino acids, called essential amino acids, can only be obtained from eating and digesting protein-rich foods—beef, poultry, fish, eggs, dairy, nuts, seeds, and legumes. While humans can probably survive on a diet of limited carbohydrates, they cannot live without a sufficient supply of essential proteins from various foods.

Low-fat Diets (only 20-30% of daily calories come from fats)

• Weight Watchers is considered by some to be among the most consistent weight loss programs over the past 40 years, helping literally thousands of people to lose weight and keep it off. The newest version combines healthy nutrition, effective calorie control, and livability. It teaches people how to eat smarter portions and make healthier, more filling food choices. While no foods are prohibited each food

is assigned "points" based on its calorie, fat, and fiber content. Every dieter has a targeted Daily Points Range based on their specific body weight and activity level. Under this low-fat system, about two pounds per week can be shed. Much of the success is due to the Weight Watchers support system that keeps dieters connected to each other and support staff. Members can get support online and at meetings in most communities. This fee-based program offers diet tools, recipes, restaurant guides, meal trackers, and other helpful techniques. • Jenny Craig diet, another well-known and popular program, is also low-fat by promoting pre-packaged meals (mostly frozen) that are 60% carbohydrates, 20% protein, and 20% fat, supplemented with fresh fruits and vegetables and low fat dairy products. There are three levels to the program: 1) Dieters adjust to the program by eating the foods they already like but in small portions; 2) Dieters learn how to boost their energy and lose weight through regular physical activity; 3) Dieters learn how to continue with a healthy lifestyle so that weight loss is maintained. Overeating is regarded as largely an emotional issue, which can be successfully addressed and managed by making positive life changes. The ultimate goal of the Jenny Craig program is to empower individuals to plan their own menus so they can shop, cook and socialize with foods. Very Low-fat Diets (0-19% of daily calories come from fats) •Pritikin Diet, introduced as a combined diet and fitness plan in the late 1970s, advocates a very low fat/high fiber carbohydrate-rich diet based largely on vegetables, grains, and fruits, and at least 30 minutes of daily aerobic exercise, weekly weight training, and daily stretching. Dr. Nathan Pritikin’s book, also a New York Times Bestseller, has sold more than 10 million copies worldwide. A central principle in diet is caloric density. By eating low caloric density foods at every meal (e.g., brown rice, oats, dark greens, potatoes, squash, beans, apples, strawberries, and bananas) you can eat as much of them as you want. By combining the leanest portions of animal protein with plenty of these vegetables and fruits, you can reduce your caloric density and lose weight. The Pritikin plan is consistent with numerous research outcomes that demonstrate that regular exercise in combination with diet modification contribute significantly to chronic disease reduction, including a diet based on whole foods high in fiber and nutrient density along with the elimination of refined carbohydrates and fatty foods (Roberts & Barnard, 2005). It should be noted as well that proteins, per se, are not the problem. In fact, it is possible that by eating more protein, especially vegetable protein, while cutting

back on easily digested carbohydrates benefits the heart. In a 20-year prospective study of 82,802 women, those who ate low-carbohydrate diets that were high in vegetable sources of fat or protein had a 30 percent lower risk of heart disease, compared with women who ate high-carbohydrate, low-fat diets. But women who ate low-carbohydrate diets that were high in animal fats or proteins did not have a reduced risk of heart disease (Harvard School of Public Health, 2010).

Key Concepts: Glycemic Index (GI)

The Glycemic Index is a ranking of foods based on the rate at which blood glucose levels rise when a particular food is consumed. Carbohydrates that break down quickly during digestion, releasing glucose rapidly, have a high GI; carbohydrates that break down more slowly, releasing glucose gradually into the bloodstream and helping to keep blood sugar levels relatively constant, have a lower GI. When blood sugar rises too high the brain signals the pancreas to release additional insulin to compensate; excess glucose is then stored as fat. GI is not related to portion size per se but the amount of food consumed and how it is prepared creates a glycemic load that triggers the body’s overall glycemic response. GI Examples: Category GI Index Foods Low 55 or less Meat, grains, fruits and vegetables, nuts, eggs, milk Medium 56-69 Whole-wheat products, sweet potatoes, long-rain rice, candy, ice cream, sucrose High 70 and above Potatoes, white bread, popcorn, watermelon, glucose

Low-calorie Diets •Slim-Fast Diet involves four steps to weight loss: portion control, sensible eating, moderate physical activity (30 minutes per day), and diet support. The Slim-Fast

plan requires six small meals/snacks on a daily basis. It is recommended that dieters consume Slim-Fast products (diet shakes, soups, pasta, meal-in-one bars, and nutritious snacks). Message boards, online chats, success stories are designed to provide timely encouragement. No calorie counting is necessary and no specific foods are forbidden. While you can still eat your favorite foods, the plan emphasizes lean protein, fruits, and vegetables.

Key Concepts: Fiber

Dietary fiber is the indigestible part of plant foods. Fiber (aka roughage), consisting of carbohydrates and a woody compound known as lignin, alters the content of foods in the gastrointestinal tract and changes how nutrients and chemicals are absorbed into the bloodstream. There are two types of fiber, and plants contain both types but in varying amounts. Soluble fiber sources include oats and barley, legumes, vegetables such as broccoli, carrots, sweet potatoes and onions, and some fruits, such as, bananas, berries, and plums. Soluble fiber absorbs water and becomes gelatinous, and is then fermented in the colon resulting in gases and active byproducts. Insoluble fiber provides bulk, softens the stool, and shortens transit time through the intestinal tract. Major sources of insoluble fiber are whole grains, bran, nuts and seeds, potato skins, some fruits such as avocados and bananas, and vegetables such as green beans, celery, zucchini, and cauliflower.

Very low-calorie Diets •Very low-calorie diet (VLCD) is typically a doctor-supervised diet that uses commercially prepared formulas to promote rapid weight loss in patients who are moderately to extremely obese, that is, with a body mass index (see Key Concepts, below) over 30. The diet, usually in the form of liquid shakes or bars, replaces all food intake for several weeks (or months) and can produce significant results, the loss of 3-5 pounds per week and averaging 44 pounds in twelve weeks. Under

these extreme conditions dieters need to supplement their intake with appropriate levels of vitamins and micronutrients. People on a VLCD consume less than 800 calories per day and should also be enrolled in a comprehensive weight-loss treatment program that includes behavioral therapy, nutrition counseling, managed physical activity, and/or drug treatment.

VLCD side effects often include fatigue, constipation, nausea, or diarrhea but these conditions usually improve within a few weeks and rarely prevent patients from completing the program. The most common serious side effect is gallstone formation, which often develops in people who are obese, especially women. Very little information exists regarding the use of VLCDs with older adults, and care should be taken in their application with dieters over the age of 50 (U.S. Department of Health and Human Services, 2008).

What does all of this really mean? Are there some common denominators in all of these diets? The simple answer is, “Yes.” By controlling portions (e.g., through meal replacement) you control consumed calories. By limiting fat and starch intake you control consumed calories. By burning more calories than you consume through increased exercise and/or portion control you eventually lose weight. Bingo!

Key Concepts: Sugar (Sucrose) Sugar refers to a type of digestible carbohydrate, characterized by a sweet flavor, that is derived from sugar cane and sugar beets. Upon ingestion, sucrose is an easily assimilated macronutrient that provides a quick source of energy, provoking a rapid rise in blood glucose. Over consumption of sucrose has been linked with adverse health effects including tooth decay and an increased risk for chronic disease. Research suggests that excessive consumption of sugar-sweetened drinks along with physical inactivity may be linked to the development of obesity, insulin resistance, pre-diabetes, and metabolic syndrome.

“Miracle” Diet Drugs Imagine taking a daily pill that sheds pounds without the need for exercise, improved eating habits, or a lifestyle makeover. If it sounds too good to be true, it probably is. The predecessors of today’s diet drugs often contained ingredients that were accompanied by dangerous side effects. Amphetamine-based diet pills were popular in the 1960s, but increased the user’s blood pressure and heart rate, created a serious dependency problem, and often led to bouts of depression. In the 1970s an over-the-counter appetite suppressant, phenylropanolamine (PPA), became popular. Unfortunately, it elevated blood pressure and caused hemorrhagic strokes in healthy, young adults. It was pulled from the market by the FDA in 2000. Next came the wildly popular fen-phen—the combination of phentermine and fenfluramine. Physicians wrote millions of prescriptions each month only to learn later that there were life-threatening side effects. Class action lawsuits followed as some users developed pulmonary hypertension and heart valve disease. Billions in payouts followed as drug makers experienced profound financial losses. And, who can forget the Metabolife diet pill debacle in which thousands of adverse effects and over 150 deaths were linked to its ephedra-based “herbal dietary supplement,” finally banned by the FDA in 2004. Two diet drugs are currently available by prescription and several more are in the wings undergoing clinical trials. Meridia (sibutramine) is an appetite suppressant and Xenical

(orlistat) is a so-called “fat-blocker.” These drugs can help you lose 5 to 20 pounds in six months, with minimum side effects, provided you add regular exercise and healthier eating to your daily regimen. By the way, Meridia, which alters your brain chemistry, can also raise blood pressure and should not be taken by people on antidepressants or with heart disease, liver, and kidney problems. Xenical disables pancreatic enzymes that are involved in fat absorption. However, pushing fatty foods thru the intestines in this way results in some inelegant side effects, such as, gas and rectal discharge. Since the drug is taken with meals when they are consumed it doesn’t help with between-meal snacks, a major issue for many over-weight individuals. Off-label drug use, prescribing drugs that were not intended for weight loss but which have it as a side effect, has been widely embraced by physicians and other health-care practitioners, insurers, pharmaceutical companies, and even the FDA. The list includes drugs originally intended for attention-deficit disorder, depression, diabetes, sleep disorders, and smoking. Obviously, not everyone is a good candidate for weight-loss drug therapy and, in off-label use, great care must be taken by both the physician and patient. One commentator likened it to “medical bungee jumping” (Snyderman, 2009). Why Diets Usually Don’t Work

Successful weigh loss involves five steps: you have to want to lose weight to the point you are ready to make some basic life changes, you must forget everything you think you already know about weight loss, you must systematically eat less (portion control) but eat more often, you must exercise a lot more, and get a good night’s sleep. Weight regulation is a complicated bio-chemical process that can be influenced by lots of factors under your immediate control, such as, attitudes and habits of friends and family, stress, emotional imbalance, hormones, taking certain

prescription drugs that work against weight loss, smoking, lack of exercise, eating everything in front of you, and eating the wrong foods. This is why so many “wonderful” diet regimes eventually fail. Dieters focus on one or two of these variables, as a rule, ignoring the other important ones just listed. At the end of the day, the golden rule of dieting is simply “calories in, calories out.” What is a calorie, anyway? It is a measure of the energy potential in food. To get an idea of how this works, think of your body as an “energy account” into which you make daily deposits by eating food, converting it into energy, and making energy withdrawals as you need them. The withdrawals involve burning calories on the basis of your basal metabolism rate (BMR) (see Key Concepts, below) and through physical activity (Snyderman, 2009). To lose one pound you will need to burn about 3,500 calories. This can be done by eating fewer calories, burning more calories through exercise, or a combination of both. The

chart below will give you some idea of what kinds of foods you would have to forego or effort expended on a daily basis for one week in order to lose one (1) pound in weight. Goal: Daily Food Strategy Daily Exercise Strategy Lose one pound in Don’t eat large blueberry 45-minutes of intense body weight @ 500 muffin with butter cycling, Thai boxing calories/day Don’t eat 4 ounces of 45-minutes of rock potato chips climbing Don’t eat the Big Mac 45-minutes of step Aerobics Don’t eat two chocolate Walk for one-hour at iced donuts with sprinkles 3 miles per hour

No one said losing weight was going to be easy—and if they did, hang on to your wallet.

Key Concepts: Calories Calories are units of energy, and are neither good nor bad. A single calorie refers to the amount of energy necessary to raise the temperature of 1 gram of water one degree centigrade. A food calorie is actually 1,000 calories, or the amount of energy required to raise 2.2 pounds of water (one kilogram) 1 degree centigrade. Calories come from only four types of food: carbohydrates, fat, protein, and alcohol. Different foods contain different amounts of energy, or calories. For example, carbs and proteins provide 4 calories per gram; alcohol provides 7 calories per gram; and fat provides 9 calories per gram. But calories are all the same whether they are connected with celery, wheat bread, or chocolate. Through a process known as metabolism the body breaks down food molecules (organic matter) in order to release the energy (calories) within them in the form of amino acids, fatty acids, and glucose. The body stores for future use energy it does not need at the time of metabolism in the form of fat cells on your belly, thighs, hips, buttock, arms. Increased activity—thinking, breathing, digestion, physical activity--results in increased metabolism as bodily fuel needs rise. The opposite is also true. Therefore, weight gain is the result of increased intake of food, decreased activity, or some combination of both (The New York Times, 2010).

Do This, Get Free (and Slimmer)! If you really, really want to lose weight (and it requires that level of personal commitment), begin by critically assessing where you are on the Body Mass Index (see Key Concepts, below). Understand that this is only an approximation that does not actually measure body fat directly. This is, however, a useful screening tool. Also, be mindful that BMI interpretations differ by age, gender, and ethnicity. Here are some other important variations (Centers for Disease Control, 2010):

• At the same BMI, women tend to have more body fat than men • At the same BMI, older adults, on average, tend to have more body fat than

younger adults • Highly trained athletes may have a high BMI because of increased muscularity

rather than increased body fatness

Key Concepts: Body Mass Index (BMI) Body Mass Index (BMI) is a number that predicts with reasonable accuracy the body fatness of most people. It is easily calculated from your weight and height. Here is the formula:

weight (lb) / [height (in)]2 x 703

Calculate BMI by dividing your weight in pounds (lbs) by height in inches (in) squared and multiplying

the total by a conversion factor of 703

Example: Weight = 150 lbs, Height = 5'5" (65") Calculation: [150 ÷ (65)2] x 703 = 24.96

Next, go to the table below and determine where you fall along the index.

Knowing your BMI is useful for at least two reasons. First, it gives you a starting point for getting your weight (and life) under control. Second, it indicates important health risk factors about which you should be aware. According to the National Heart, Blood, and Lung Institute (1998), overweight and obese individuals are at increased risk for many diseases and chronic health conditions, including:

• Hypertension • Dyslipidemia (for example, high LDL cholesterol, low HDL cholesterol, or high

levels of triglycerides) • Type 2 diabetes • Coronary heart disease • Stroke • Gallbladder disease

• Osteoarthritis • Sleep apnea and respiratory problems • Certain cancers (e.g., endometrial, breast, and colon)

BMI TABLE

BMI WEIGHT STATUS Below 18.5 Underweight 18.5 – 24.9 Normal 25.0 – 29.9 Overweight

30.0 and Above Obese

So, now you know your BMI. What’s next? Actually, several things. You need to get smarter about food (see Blog post, “You Are What You Eat…and Drink”), exercise, and weight management. Calculate your Basal Metabolism Rate and daily caloric needs in order to establish a caloric baseline (see Key Concepts, below). Weight and fitness goals and milestones would be helpful. A life plan that engages a support network also works well for many people. Consider one of the diets reviewed above or other good ones if you need structure and encouragement. Also, there are some excellent websites out there related to the topics and issues in this post, software applications, and calorie and exercise monitoring devices (e.g., Garmin 205 and bodybugg).

Key Concepts: Basal Metabolism Rate (BMR) Basal Metabolism Rate (BMR) is the rate at which you must burn calories to maintain basic body functions—breathing, thinking, digesting, sleeping--while doing little else. This is the minimum caloric requirement needed to sustain life in a resting individual. Your individual BMR accounts for up to 70 percent of your daily caloric need but this percentage varies based on your actual metabolism rate, gender, age, weight, body surface area, body fat percentage, diet, body temperature/health, hormonal activity, and exercise level.

After calculating your BMR you can add an additional factor, level of physical activity, to determine your total daily energy expenditure (TDEE). By combining both the BMR and typical level of physical activity, you are able to establish a clear baseline for your daily caloric needs. This is extremely useful for purposes of dieting since you can only burn fat with a negative calorie deficit, that is, using more caloric energy than you are taking in

through the consumption of food. A calorie deficit can be created through diet, exercise, or preferably a combination of both.

The BMR formulae below are reasonably accurate for all but the most lean/muscular and obese individuals

BMR Calculation Formulae Women: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in

inches ) - ( 4.7 x age in years )

Men: BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) - ( 6.8 x age in years )

BMR Activity Multiplier

Sedentary = BMR X 1.2 (little or no exercise, desk job)

Lightly Active = BMR X 1.375 (light exercise/sports 1-3 days/wk) Moderately Active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)

Very Active = BMR X 1.725 (hard exercise/sports 6-7 days/wk) Extremely Active = BMR X 1.9 (hard daily exercise/sports & physical job

or 2X day training, i.e. marathon, contest etc.)

Key Concepts: Calculating Your BMR

Calculating your BMR requires nothing more than basic arithmetic skills. For example, let’s say you are 60 years old, male, 5’ 10” tall, weigh 190 lbs., and are moderately active. Using the BMR formula for males:

66 + (6.23 x 190) + (12.7 x 70) – (6.8 x 60) or

66 + (1183.7) + (889) – (408) or

2138.7 – 408 or

= 1730.7 (BMR calories)

1730.7 (BMR) x 1.55 (Activity Factor) = 2,682.6 calories per day to sustain oneself. To lose weight, a diet deficit of 500 calories daily would result in the loss of one pound per week.

The Most Effective Weight-Loss Strategy The most effective weight-loss strategy combines regular, vigorous exercise with choosing healthy foods in appropriate amounts. In a recent meta-analysis of 43 different studies on exercise and weight loss, regular exercise was an effective intervention, particularly when combined with diet management (Shaw, Gennat, O'Rourke, & Del Mar, 2006). Exercise resulted in small weight losses across all the studies. However, exercise combined with a low-calorie diet resulted in a greater weight reduction than diet alone. Likewise, increasing exercise intensity increased the magnitude of weight loss and there were significant benefits in other outcome measures such as serum lipids, blood pressure, and fasting plasma glucose. Collectively in this group of studies, exercise on average consisted of at least 30-minutes moderately-intense activity on most days, such as, walking, jogging, cycle ergometry, weight training, aerobics, ball games, and calisthenics. Since glycogen is preferentially burned during the first 20 minutes of exercise, at least 30 minutes of exercise is necessary to begin burning fat stores (Dachs, 2007).

Weigh Loss Is Independent of Diet Composition Part of the dieting mythology that adds to the confusion about weight control is the notion that certain foods are evil—like salty snacks, soft drinks, cookies, ice-cream. This is the wrong approach. Food is fun, it’s part of life, and a lot of it tastes good. You can eat just about anything so long as you do so responsibly. Remember, “every bite counts!” Eating fatty foods doesn’t make you fat. Eating a variety of foods in appropriate proportions—fats, complex carbohydrates, protein, fruit, and vegetables---will help you stay healthy and maintain the proper body weight for your age, height, and activity level. However, there is substantial scientific evidence supporting the benefits of eating lean proteins (e.g., fish, poultry), about 30 percent of your daily caloric intake, in association with physical activity (Paddon-Jones, et al., 2008). Moderate protein diets, when compared against conventional diets, which typically are high in carbohydrates, help curb appetite and produce sustained weight loss along with favorable long-term changes in body composition and blood lipids (Laymen et al., 2009).

Meal Frequency For the past 40 years the question of the advantages, if any, of eating smaller but more frequent meals has challenged nutritionists. As the theory goes, eating small meals throughout the day while not increasing one’s caloric load can lower cholesterol, promote weight loss, improve energy levels, boost metabolism, and preserve lean muscle mass. The research findings are at best mixed, with some studies finding very modest decreases in cholesterol levels and lower blood pressure from eating more frequently but no specific energy advantage (Parks & McCrory, 2005; Bellisle, McDevitt & Prentice, 1997). On the other hand, there may be some negative health impacts from eating only one meal per day or irregular eating. These include significantly higher blood pressure and cholesterol levels (LDL and HDL), glucose intolerance, insulin insensitivity, and lower cortisol levels, although the latter could be due to diurnal variations (Stote et al. 2007; Carlson et al., 2007; Farshchi, Taylor & Macdonald, 2005). Skipping meals or engaging in intermittent fasting, despite lower caloric intake, appears to have more health negatives than positives, and may actually reduce fat-burning metabolism. This continues to be a very active research area. Questions needing clearer research answers include both the timing of meals during the day and their frequency. At a lifestyle level, eating more frequently while not increasing caloric intake can be beneficial by increasing one’s food focus while decreasing hunger and snacking throughout the day.

Key Concepts: Cortisol Cortisol is a hormone produced by the adrenal gland, and is needed for nearly all dynamic processes in the body, from blood pressure regulation and kidney function, as well as glucose level maintenance, fat building, muscle building, protein synthesis and immune function. One of cortisol’s more important functions is to act in concert with thyroid hormones at the receptor-gene level. Cortisol makes the thyroid work more efficiently. A specific amount of cortisol—not too high and not too low—is very important for normal thyroid function (Virginia Hopkins Health Watch, 2009).

Aging and Weight Maintenance As adults grow older their hormone levels change and metabolism slows down. Usually their level of physical activity also declines which results in the replacement of muscle mass with body fat. Together, these independent biological mechanisms often result in weight gain for both men and women during their 50s and 60s, the dreaded middle age spread (Evans & Cry-Campbell, 1997). The obvious solution, of course, is to move more

and eat less (portion control) and eat more frequently (4-5 times daily) (Williams & Wood, 2006).

And for those motivated enough to engage in lifestyle changes that will produce genuine weight loss, it is critically important to avoid the diet roller coaster. Going on a diet to lose weight only to gain to back again is unhealthy and, simply, will make you crazy. By the way, the number of fat cells we have stays relatively constant across the lifespan after their establishment in our teenage years (Spalding et al.,

2008). That means when you gain weight your existing fat cells get larger in terms of volume. When you lose weight they shrink and become metabolically less active. Sorry.

Postscript Disclaimer: All dietary and supportive lifestyle changes must be personalized. Moreover, the research-based generalizations offered here about dieting assume healthy adults, broadly defined, who are motivated toward better weight management. Individuals with special health issues, such as diabetes, hormonal imbalance, or heart, liver, or kidney disease should consult a physician or licensed dietician before embarking on any weight-loss program.

Copyright 2010 Stephen F. Barnes, Ph.D.

San Diego State University Interwork Institute

Additional Reading Synderman, N.L. (2009). Diet myths that keep us fat: And the 101 truths that will save your waistline—and maybe even your life. New York: Crown Publishing. Yager, S. (2010). The hundred year diet: America’s voracious appetite for losing weight. New York: Rondale.

Informational Websites

About BMI for Adults (Centers for Disease and Prevention) http://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html BMR Calculator http://www.bmi-calculator.net/bmr-calculator/

Diets A-Z http://www.webmd.com/diet/evaluate-latest-diets

REFERENCES

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1. Tomato on plate from http://leangenix.com/blog/?p=19 2. Feet on scale from http://images.beachbody.com/newsletter_p90x/045/web_issue_045.htm 3. Scissors to Food Pyramid from http://www.barbarapotashkin.com/low_carb.html 4. Fat Loss for Idiots from http://fatlose4idiot.com/ 5. Low fat cottage cheese from http://www.thekitchn.com/thekitchn/health/diet-conscious-when-

do-you-use-lowfat-substitutes-062737 6. Slim-fast products from http://www.boncherry.com/blog/2009/12/04/slim-fast-recall-every-

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8. Miracle diet drugs from http://www.celebritydietdoctor.com/tag/diet-pills/ 9. Fat cat from http://crazy-picsblog.blogspot.com/2008/04/funny-fat-animals.html 10. Blueberry muffin from http://www.thedeliciouslife.com/blueberry-muffins-and-why-i-have-

2499/ 11. Big Mac from http://pzrservices.typepad.com/advertisingisgoodforyou/2007/08/index.html 12. Donuts with sprinkles from http://mashable.com/2010/04/19/dunkin-donuts-finalists/ 13. Woman stretching from http://www.nutralegacy.com/blog/general-healthcare/what-is-bmr-

basal-metabolic-rate/ 14. Carrots from http://www.livestrong.com/article/137427-what-vitamins-regulate-thyroid/ 15. Lemon meringue pie from

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