Thursday, October 31, 2013

Weight rebound after a low calorie diet: what works to prevent it? by Jerry Brainum

It's not that hard to lose excess body fat. All it takes is willpower and perseverance. No matter what type of diet that you choose, you need to consume less calories that you use through activity, including exercise.As to the best type of diet to use, there is no one size fits all formula, despite the plethora of diet books that claim the contrary. And the notion promulgated by some self-serving experts that "calories don't count," is also utter nonsense, since it goes against the physical principles of what causes weight, or more specifically, fat loss in the body. What you lose during a diet also makes a difference. The ideal is to lose excess body fat without sacrificing lean tissue, mainly muscle. When you lose muscle from extreme dieting, your resting metabolic rare declines, a scenario that favors rapid weight return. The primary cause of lost muscle mass from dieting is either too extreme a drop in calories, such as a starvation diet that doesn't supply sufficient protein to support lean mass maintenance, or a lack of exercise, especially resistance training.
    The truth is that 97 percent of those who go on a diet to lose body fat gain it all back. This is more likley to occur with more extreme diets, such as diets that feature a total daily caloric intake of under 1,000, or a diet that emphasizes zero carbohydrate intake. Such diets go against the natural grain of body metabolism, and the body reacts to such extreme measures by overcompensation, such as a reduction in thyroid hormone output that favors the regain of lost weight.
   But are there things you can do to prevent the return of lost body fat following a diet?  One way is to not try to go on a crash diet that is too low in calories. Instead aim for a more gradual weight-loss of about two pounds per week. This allows the body and the brain to adjust to the weight loss, and ensures greater long-term body compliance. The odds of maintaining lost weight following a crash diet are low, and only those with a zen-like degree of willpower are able to accomplish that goal.
    A newly published meta-analysis (an analysis of prior studies that is brought to a rational conclusion) examined various factors that may aid in keeping the weight off following a diet. The analysis looked at 20 studies involving 3,017 participants. The type of diets examined in the study were either low calorie, defined as 1,200 calories a day or less, and very low calorie, defined as 800 calories a day or less. The study noted that the main reasons for weight regain after a diet include adaptive thermogenesis, whereby the body adapts to a lower calorie intake, and increasing calories then results in weight gain; increased release of appetite-stimulating hormones, such as ghrelin; and simply a relapse in the same eating habits that produced excess fat in the first place.
    The study found that anti-obesity drugs seemed to help keep weight off after a diet. The study focused on two such drugs. Orlistat inhibits fat absorption, but has a high rate of side effects. The other drug mentioned was sibutramine, which reduces appetite, but also can cause heart problems. For that reason, it was removed from the market three years ago. But it still often shows up surreptitiously in various "fat-loss" supplements. In truth, perhaps the most effective fat-loss combination consisted of ephedrine and caffeine. This combination was so effective that it threatened the sale of more ineffectual diet drugs, leading to the eventual ban of ephedrine under the guise that it was toxic, which was nonsense. As such, current diet drugs are, in a word, crap, despite the finding of this new study.
   The study also suggested that meal replacements can aid the prevention of rebound weight gain. They are usually low in calories, and allow the dieter to know precisely what they are consuming in terms of calories and nutrient content. Most also are higher in protein, which helps to maintain lean mass, a key component of keeping the weight off.
   A high protein diet was also suggested as an effective tool for preventing weight- regain. High protein intake (at least 30% of total calories) not only helps maintain muscle mass through offsetting catabolic effects in muscle, but also increases feelings of satiety, thus helping to prevent overeating. Higher protein foods also produce a greater degree of diet-induced thermogenesis, which means greater resting calorie burn.
   Consumption of low glycemic index foods, or foods that do not overly stimulate a high blood glucose level or release of insulin, also can provide some advantages for those who want to prevent weight rebound effects. Low glycemic index foods are most often rich in fiber, which itself provides some satiety effects.
   Perhaps the most controversial aspect of this new nutrition meta-analysis is the suggestion that exercise doesn't aid in keeping weight off after a diet. Since exercise does burn calories, it's hard to understand how this could be so. On the other hand, some types of exercise result in a caloric compensation effect, in which the appitite is stimulated to a degree that results in not only a return of calories burned from exercise, but also additional calories. This, or course, favors rebound weight gain. However, this depends on what type of exercise you do. If your exercise consists solely of aerobics and stretching, the exercise will do little to prevent weight regain. But resistance exercise because if its greater involvement of larger muscle groups and higher muscle intensity level, does favor a higher resting metabolic rate. That, in turn, would help to prevent regaining lost fat.
   Finally, the meta-analysis found that fat-loss supplements don't help to prevent weight regain after a diet. Again, this seems contradictory, since most such supplements work by containing ingredients to both blunt appetite, as well as boost thermogenic effects, which would lead to greater calorie use at rest. But the truth is, despite the hyperbolic ads for such "fat loss" supplements, they provide only a minor adjunctive weight-loss effect. What this means is that the majority of fat loss comes from a combination of exercise and diet adjustments. The minimal thermogenic effects of the fat loss supplements  provide relatively minor effects, if any. Not only that, but many of the often exotic herbal ingredients of such fat loss supplements have little or no solid human research to prove their effectiveness. The only "proof" is often a few esoteric animal studies, which may or may not be applicable to human physiology.

Johansson, K, et al. Effects of anti-obesity drugs, diet, and exercise on weight-loss maintenance after a very low calorie diet or a low calorie diet: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr 2013: in press.

©,2013 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited.

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