The truth about weight-loss: debunking magical thinking about dieting
Dr. Lauren Muhlheim is an American psychologist who has worked in the field of eating and weight-related disorders since 1991. She sees patients at Parkway Health Shanghai Cente and the Community Center and is President of the Shanghai International Mental Health Association.
Appeared in Parkway Health newsletter November 2009.
Slimming, however, has to do with fantasies…..Why people choose to diet, when they diet, how they go about dieting – these are determined by prevailing fantasies about the body, its weight and its fat. (Never Satisfied: A Cultural History of Diets, Fantasies, and Fat by Hillel Schwartz, 1986)
When it comes to weight loss, many people seem extremely susceptible to magical thinking. Other than the Fountain of Youth, an easy, painless solution to staying thin may be the world’s most coveted goal. Wouldn’t it be great if one could take a pill, eat the right combination of foods, or somehow become thin with no effort?
Myths and Magical Thinking
Every one of us is susceptible to exactly this sort of magical thinking in the area of weight loss. The diet industry knows and preys upon this. Diet doctors publish diets that offer quick weight loss solutions; infomercials advertise special exercise equipment and miracle thigh cream; and companies offer nutritional supplements that often contain dangerous chemicals or hormones. Over 18 million prescriptions were written in 1996 for the combined protocol of Fenfluramine and Phentermine (Fen-Phen); only a year later the drugs were withdrawn from the market after studies showed they caused heart problems. This is far from a recent phenomenon; people have peddled weight-loss elixirs for more than a century.
Many of these solutions offer “scientific” rationales for their promise of rapid weight loss with no real scientific support. Some popular diets such as the South Beach Diet and the Grapefruit Diet advocate certain food combinations that reduce fat absorption or increase calorie-burning. The famous Atkins diet purported that fat and protein could not cause weight gain in the absence of carbohydrate consumption. Weight loss pills and supplements lay claim to compounds with unique fat-burning properties. Numerous effortless solutions offered are merely fantasies.
The Simple Science Behind Weight Loss
There is a simple science to weight gain and loss. Understanding this science helps to dispel some of the myths. In an article I co-authored in 1995 for the American Journal of Clinical Nutrition, Steven Heymsfield et al. wrote, “Few dietary components are surrounded by more myths than the calorie.” To understand the science of weight loss, only a few simple concepts are required.
First, a calorie is simply a unit of energy: technically speaking, the amount of energy (or heat) it takes to raise the temperature of one gram of water by 1 degree Celsius. The calories we measure in foods are actually kilocalories (the equivalent of 1000 calories).
Second, your metabolic rate is the measure of the average rate at which your body burns energy – standard metabolic measures include the resting metabolic rate (energy burned while the body is resting) and 24-hour metabolic rate (the amount of energy burned in 24 hours). Your metabolic rate is primarily determined by your body’s fat-free mass, a measure of the body mass devoid of all fat.
Third, body fat is a store of energy. Through recent scientific techniques such as the use of chemical markers to accurately measure energy expenditure, researchers have been able to demonstrate that energy intake in excess of energy expenditure translates into increased body fat at a rate of about 3,500 kilocalories per pound. This is a very consistent result
Finally, energy can be neither created nor destroyed (this is known as the first law of thermodynamics). In the science of weight loss, this means that if your caloric intake equals your energy expenditure, your weight will be stable. If your caloric intake is greater than energy expended, the balance goes to body fat. In order to lose a pound of fat, you need to create an energy deficit of 3,500 kilocalories – that is, cutting 3,500 kilocalories from your diet, or expending an additional 3,500 kilocalories through exercise.
That is all the science you need to know to be a successful dieter. In addition, to their greater fat mass, obese individuals also tend to have a higher fat-free mass than the non-obese (muscle to carry the additional weight). With extremely rare exceptions, this implies the obese have a higher metabolic rate and use more energy. Greater caloric intake is required to maintain this weight.
Energy Balance
Starting a diet creates a negative energy balance in the dieter. As a result, the energy store of body fat, and the fat-free mass required to carry that fat, decreases. This leads to a decrease in metabolic rate, which in turn balances the reduced intake. Weight will not continue to be lost beyond a certain point if the dieter sticks to the same eating plan. This is the explanation behind dieting “plateaus” and the old set-point theories. If a dieter goes back to eating what they were eating when they were much heavier, they are using less energy than they are bringing in, and the weight will be regained.
Research: What Works and Doesn’t
There are in fact numerous ways to lose weight, and almost any reduction in food intake will produce an initial weight loss. Today there are camps advocating several different approaches to weight loss. A recent study funded by the US National Institutes of Health and published in the New England Journal of Medicine compared overweight participants randomly assigned to one of four different approaches over a two-year period: a low-fat, average protein, high carb diet; a low-fat, high-protein, average carb diet; a high-fat, average protein, average carb diet; and a high-fat, high-protein, low carb diet. The results demonstrated that reducing calories achieved weight loss regardless of which of the three nutrients was emphasized– the actual mix of these calories made no difference in the result. Another important finding was that participants who attended counseling sessions lost more weight than those who didn’t.
While initially losing weight can be easy for many, maintaining it is usually much more difficult. Numerous studies show that regardless of method, the majority of weight lost (as much as 95%) is ultimately regained. A 2007 study funded by the US National Institute of Mental Health conducted by researchers at UCLA analyzed 31 long-term dieting studies and found that obese subjects were able to lose 5 to 10 % of their starting weight in the first six months of the studies. However, 2 to 5 years after weight loss, most subjects had regained all of this weight. Even worse, 30-60% of subjects ended up heavier than they had been at the start.
A number of factors contribute to weight regain. These include reductions in metabolic rate, susceptibility to high calorie foods after a period of deprivation, the prevalence of these foods in today’s society, and the loss of the reinforcement of weight loss. With the beginning of the maintenance phase, the most satisfying aspect of weight loss ceases and the individual may have difficulty maintaining motivation given the continued cost of reduced intake and increased expenditure without the immediate reinforcement of seeing the scale go down.
With all of these interfering factors, it is important to choose a weight loss regimen that you can maintain over time.
The National Weight Control Registry in the United States keeps tabs on more than 3,000 people who have lost at least 30 pounds and maintained that loss for at least one year. The two common denominators among these successful long-term weight losers are exercising regularly and cutting calories. 98% of Registry participants report that they modified their food intake in some way to lose weight. 94% increased their physical activity, with the most frequently reported form of activity being walking. Almost half of the registry participants (45%) lost the weight on their own and the rest (55%) lost weight with the help of some type of program. Fewer than 5% followed diets such as the Zone or Atkins. Fifty percent ate the same food they had always eaten but restricted portion size. Fifty percent counted calories.
To lose weight successfully, you need to reduce calories ingested and increase calories burned. You should pick an eating plan that is healthy and flexible and can be maintained for a long time –get past the idea being of on and off a diet and think instead about eating healthy for life. Weight Watchers is a great example of such a plan. You should also plan an exercise program that starts gradually and builds as you get stronger.
In the next article, I will discuss how principles of Cognitive Behavioral Therapy can help you increase and maintain motivation, learn to manage hunger and cravings, enjoy what you eat more, deal with and prepare for sabotaging influences, counter sabotaging thoughts, and manage setbacks.