DOES DIETING WORK?
There are conflicting views on the value of weight-loss diets. Some believe that if individuals have willpower and if they diet they can lose an unlimited amount of weight. Others believe that weight loss attempts are rarely successful and weight regain invariably occurs.
There are many questions to ask when evaluating “does dieting work?” Do dieters continue to lose weight? Does some of the lost weight return? Do some dieters gain back more weight than they lost? Women participating in a weight-loss program reported their goal weight as an average 32% reduction in body weight [G.D. Foster et al; J Consult Clin Psychol. 1997;65:79-85]. After 48 weeks of treatment and an average loss of 35 lbs, 47% of women did not achieve weight loss they associated with success. Thus what are achievable goals?
What is Occurring in the USA?
In the USA obesity has increased dramatically [K.M.Flegal et al; 1999-2000. JAMA. 2002;288: 1723-1727][ 1960-1994. Int J Obes Relat Metab Disord. 1998;22:39-47]. In addition the number of adults trying to lose weight by dieting and the amount of money spent on weight-loss has also increased. Using the most recent data from the CDC’s National Center for Health Statistics [NCHS] more than one-third of U.S. adults (34.9 percent) were obese in 2011 to 2012. Approximately half of all adults are trying to control weight, with about one third of men and nearly one half of women trying to lose weight. In addition we spend approximately $50 billion per year on weight-loss efforts [E.C. Weis et al; 2001-2002. Am J Prev Med. 2006;31:18-24].
WHY SHOULD I LOSE WEIGHT?
From a medical perspective, preventing metabolic diseases such as hypertension, type 2 diabetes, coronary artery disease, and dementia is the single most important health issue today. Obesity is associated with all of these common chronic diseases: t [S.Klein et al; Circulation. 2004;110:2952-2967].
Sustained modest weight loss is associated with health improvements: a decreased risk for type 2 diabetes, reductions in blood pressure, and improved lipid profiles . Health improvements begin to appear with weight losses of 5% to 7% [American Diabetes Association and National Institute of Diabetes, Digestion; Diabetes Care. 2002; 25:742-749].
In1998 the National Institutes of Health recommended weight loss for persons with a BMI – body mass index-of 30 or more and for persons with a body mass index between 25 and 29.9 with two or more risk factors [hypertension, type 2 diabetes, abnormal lipids, coronary artery disease];[National Institute of Health. National Heart, Lung, and Blood Insti- tute. Clinical guidelines Obes Res. 1998;6(suppl 2):51S-209S]. BMI is a person’s weight in kilograms (kg) divided by his or her height in meters squared. BMI is useful in population studies because it is easy to obtain and in general is a useful measure of health and longevity. It does not distinguish body fat weight from muscle or bone weight.
WHAT ARE THE RESULTS OF MOST DIETS?
HealthPartners Health Behavior Group in collaboration with Kaiser Permamente’s Care Management Institute completed a review of long-term weight-loss interventions. Weight-loss studies reviewed were categorized into eight types of interventions: advice alone, diet alone, diet and exercise, exercise alone, meal replacements, very-low-energy diets, and weight-loss medications (orlistat and sibutramine). In addition, a meta-analysis [a statistical technique for combining the findings from independent studies] was carried out on interventions, including diet, exercise, diet and exercise, meal replacements, and weight-loss medications. The purpose of the systematic review was to answer the questions raised above -do diets work? In studies with a minimum follow-up of 12 months mean weight loss of approximately 11 lbs. to 18 lbs. [5 to 9%] was observed during the first 6 months with a reduced calorie diet and/or weight-loss medications. However a weight-loss plateau usually occurred at approximately 6 months. In weight loss studies involving low calorie diets extending to 48 months, a mean loss of 6 lbs. to 13 lbs.[ 3 to 6%] occurred and was maintained. In studies with advice-only and exercise-alone groups experienced minimal weight loss. In summary weight-loss interventions utilizing a reduced calorie diet and exercise are associated with moderate weight loss at 6 months. Supervision and extension of the time period is beneficial. Although there is some regain of weight, weight loss can be maintained. Thus in the longer-term weight loss is increased when diet and physical activity are combined [D.J.Johns et al; J Acad Nutr Diet. 2014 Oct; 114(10): 1557–1568 ].The addition of weight-loss medications somewhat enhances weight-loss maintenance. Thus the minimum requirements of the American Diabetes Association and the National Institute of Diabetes as noted above can be achieved and maintained.
There are many people that think that diets do not work. Weight regain after a diet is your body’s evolved response to starvation [Mann PhD, Traci (2015-04-07). Secrets From the Eating Lab: The Science of Weight Loss, the Myth of Willpower, and Why You Should Never Diet Again (p. 16). HarperCollins.] In addition your genes are involved in regulating your weight. In order to compare the effect of genetics versus the environment on the body-mass index (weight in kilograms divided by the square of the height in meters) A.J. Stunkard et al [N Engl J Med 1990; 322:1483–7.] studied samples of identical and fraternal twins, reared apart or reared together in Sweden. Stunkard concluded that genetic influences on body-mass index were more important than the childhood environments.“ Genetic factors appear to be major determinants of the body-mass index in Western society, and they may account for as much as 70 percent of the variance”[Stunkard et al]. If the environment has no influence then external factors such as culture, exercise, and dietary choices have no influence on your BMI. This sounds counter intuitive but this is part of the rational of those who recommend “no diets”. The above research is correct; the interpretation however, is incorrect. The BMI has only two components-height and weight. Height in western societies is approximately 100% determined by genetics. With BMI 70% determined by genetics suggests that 40% of your weight is determined by genetics [ (100+40)/2=70]. Thus environment has a major role in determining your weight AND DIET IS VERY IMPORTANT.
The most compelling argument for “non-dieters” is the idea that each person has a genetic set weight range-the weight range you tend to be. This theory proposes a feedback and control system designed to regulate body weight to a relatively constant range -the set point weight [Hall KD, Heymsfield SB. Cell Metab. 2009;9:3–4].The body will adjust food intake and energy expenditure, to keep the body weight in a certain range. Most obese patients who lose weight on a diet will regain much of their weight loss over time [L.P.Svetkey et al; JAMA. 2008; 299:1139–48]. With diet alone a new set point is difficult to maintain. The inability of the obese dieters to keep the lower weight point suggests that their diets were ineffective in reducing a high weight “set point”. These observations are consistent with the leptin feedback loop findings. [V. Haas et al; Clin Nutr. 2010]. Leptin is a “hormone or ligand” produced by fat cells that feeds information to hypothalamic brain centers. Ligands are the molecules that allow cells to communicate. Low leptin levels increase appetite and food intake while normal to high levels appear to have little effect. Thus the body appears to protect more against fat loss then against fat gain. This is the best argument that diets do not work; however the details of food intake post diet is most important.
There are things that cause “leptin resistance” a state where high leptin levels become ineffective in reducing body fat. There is evidence that leptin resistance occurs in lean or fat subjects fed a diet high in sugar [J.R.Vasselli et al; Adv Nutr. 2013 Mar 1;4(2):164-75]. Obese people are metabolically different than the non obese in that most are or will become “insulin resistant”. This is the development of cellular resistance to the effect of the hormone insulin and this leads to over production of insulin by the cells of the pancreas and is the hallmark of type 2-diabetes. Leptin resistance is also the inability to decrease food consumption in the presence of Leptin. This actually occurs at the blood –brain barrier where leptin receptors are located. Specific types of dietary sugars [sucrose and fructose] and fats [triglycerides] are capable of inducing leptin resistance [J.R.Vasselli et al; Adv Nutr. 2013 Mar; 4(2): 164–175.]. In addition elevated insulin levels and inflammatory cytokines also produce leptin resistance. Leptin resistance and insulin resistance occur together and these two simultaneous processes may be responsible for the world-wide epidemic of obesity.[A.C. Konner and J.C.Bruning; Cell Metabolism;16(2);144-152; 2012]. Insulin resistance has also been linked to hypertension, dyslipidemia, atherosclerosis, cardiovascular disease, polycystic ovaries syndrome, and cancer. It is interesting to note that it is a diet high in sugar that causes both insulin resistance [type-2 diabetes] and leptin resistance.
HIGH SUGAR DIET/MODERN DIET—–INSULIN RESISTANCE/LEPTIN RESSTANCE—–OBESITY—–METABOLIC DISEASES
Is it possible to change your “set point” with a low sugar diet alone? Unfortunately this is unlikely [G.D.Foster et al; N Engl J Med 2003; 348:2082-2090May 22, 2003]. If diet alone will not change our set point and allow long term weight loss-what can we do? The answer is diet and exercise.
DIET AND EXERCISE TOGETHER
The combination of diet and exercise together will achieve greater weight loss and will allow longer maintenance of weight loss than either intervention alone [A.J.Orzano and J.G.Scott; J Am Board Fam Med; 17(5); 2004; 359-369]. Exercise can include many different activities-but in general can be divided into two main categories-cardiovascular or endurance exercise [walking, running, swimming, cycling] and resistance training [weight lifting]. A resistance study of elderly sedentary postmenopausal women over 16 weeks discovered a decrease in inflammatory cytokines including interleukin-6 and more importantly a decrease in leptin and resistin. Maximal strength on all measures was increased after 16 weeks [J.Prestes et al; J Sports Sci. 2009 Dec;27(14):1607-15]. Resistin is a newly discovered hormone produced by fat cells and is associated with insulin resistance and the development of type 2 diabetes [Abi Berger; BMJ. 2001 Jan 27; 322(7280): 193.]. Thus we can link exercise with weight loss through a decrease in leptin [decrease in body fat] and improved cellular metabolism [a decrease in insulin resistance through increased resistin]. Cardiovascular exercise is known to decrease appetite [S. Vatansever-Ozen et al; J Sports Sci Med. 2011 Jun; 10(2): 283– 291]. To date there are no randomized prospective weight loss trials that include a low sugar diet in combination with cardiovascular exercise and resistance exercise. I can only speculate that prolonged body fat loss is possible with a low sugar diet in combination with vigorous exercise [cardiovascular and resistance exercises]. The proof of this however can be seen in the photographs of champion amateur bodybuilders since virtually all of these competitors follow a lifestyle of a low sugar diet and both types of exercise. What appears to be important is how a person thinks about their diet and exercise or lifestyle. A healthy lifestyle is a path with no end. Knowledge of how your body works is the key to this path. If it is a race, it is the race won by the turtle and not the hare.
The additional reasons diets fail is that we are addicted to eating unhealthy food and modern society misinforms us. Sugar can be a substance of abuse and lead to a natural form of addiction [N.M. Avena et al; Neurosci. Biobehav. Rev; 2008; 32(1); 20-39]. Food addiction occurs because the brain pathways that evolved to respond to natural rewards are also activated by addictive drugs and by sugar. Sugar is noteworthy as a substance that releases opioids and dopamine and has addictive potential. The four components of addiction are: bingeing; withdrawal; craving; and cross-sensitization. Each can be demonstrated to be present with sugar bingeing. These behaviors are related to the neurochemical changes in the brain that occur with addictive drugs and with sugar.
The obesity epidemic in this country has been aided by the low cost of high glucose-containing carbohydrates. These foods (soy beans and corn) are inexpensive because their production and storage is subsidized by the U.S. government in the Farm Bill. For the past 50 years, U.S. farm policy has been directed towards driving down the price of farmed storable carbohydrates (again, corn and soybeans).
At the same time, the cost of growing fruits and vegetables has increased, as has their retail price. Low costs incentivizes the food industry to use more of these unhealthy commodities. High-fructose corn syrup is now commonly added to many foods (processed foods).In summary, the food industry has a huge financial incentive to make food with high-glycemic carbohydrates [sugars]. They also use sophisticated marketing tools. “Marketing” is defined as “whatever it takes to make you buy a specific product.” One of the most useful marketing techniques is to aim marketing messages at children, who then nag their parents to buy this or that product; then, the child may continue to buy that product well into adulthood.The food industry spends over $1.6 billion dollars marketing food to children. (HBO documentary series The Weight of the Nation, May 2012.) Most of these products are processed foods high in calories and addicting sugar.
Every month, approximately 90% of American children between the ages of three to nine years visit a McDonalds. (Fast Food Nation, Schlosser E, Mariner Books, Houghton Mifflin Harcourt, 2012.) Is it a coincidence that McDonalds operates over 8,000 restaurant-playgrounds? (Schlosser E (1/17/2001). Fast Food Nation: The Dark Side of the All-American Meal, p. 35, Houghton Mifflin Harcourt, Kindle edition.)Fast-food chains profit when children drink soda, because soda has the highest profit margin. Today, McDonald’s sells more Coca-Cola® than anyone else in the world. A medium Coke that sells for $1.29 contains roughly 9 cents’ worth of syrup. (Schlosser E (1/17/2001). Fast Food Nation: The Dark Side of the All-American Meal, p. 42, Houghton Mifflin Harcourt, Kindle edition.)
We continue to eat poorly in the belief that “labels do not lie.” Marketing companies have created labels using a selection of words that make us believe we are eating healthy food when, in fact, we are not. “Whole grain” refers to a cereal product containing the germ, endosperm and bran, and thus not refined or man-made. Yet, the stamp “whole grain” from the Whole Grains Council means the product must contain only 8 grams of whole grain per 30 grams of product, and thus is mostly not comprised of whole grains. The label stating “Made With Whole Grain” actually may mean that only a tiny amount of whole grain is present. The label “Heart Healthy,” sold by the American Heart Association for use on foods, refers to the fat and salt content of a product but not the sugar content of the product; thus, one real cause of heart disease is not even accounted for. The term “all natural” really should be labeled “stay away!” The USDA does not define foods labeled “all natural” as any different than those labeled “natural.” Foods with this labeling are usually not any different than “natural” foods, and may not be regulated, because they are not defined by the USDA. Foods labeled “natural,” according to the USDA definition, do not contain artificial ingredients or preservatives, and the ingredients are only minimally processed. However, they may contain antibiotics, growth hormones, and other similar chemicals. People often confuse “natural” with “organic” and marketers will continue to do whatever it takes to sell their products.
In summary diets fail but a healthy life-style always prevails. It takes knowledge to remain healthy. CAVIAT EMPTOR.