Weight Loss Myths Debunked – NEJM

A recent study published in the New England Journal of Medicine debunked several weight-loss myths. Instead of telling you the myth I’m going to tell you the truth for each of the myths according to the authors.
Truth number 1: Small sustained changes in energy intake or expenditure do not produce large, long-term weight changes.

“Predictions suggesting that large changes in weight will accumulate indefinitely in response to small sustained lifestyle modifications rely on the half-century-old 3500-kcal rule, which equates a weight alteration of 1 lb (0.45 kg) to a 3500-kcal cumulative deficit or increment.
Recent studies have shown that individual variability affects changes in body composition in response to changes in energy intake and expenditure, with analyses predicting substantially smaller changes in weight.
For example, whereas the 3500-kcal rule predicts that a person who increases daily energy expenditure by 100 kcal by walking 1 mile (1.6 km) per day will lose more than 50 lb (22.7 kg) over a period of 5 years, the true weight loss is only about 10 lb (4.5 kg),6 assuming no compensatory increase in caloric intake, because changes in mass concomitantly alter the energy requirements of the body.”

Truth number 2: Setting realistic goals for weight loss is NOT as important as once thought. Patients do NOT become more frustrated and lose less weight with goals that are bit more lofty.

“Although this is a reasonable hypothesis, empirical data indicate no consistent negative association between ambitious goals and program completion or weight loss. Indeed, several studies have shown that more ambitious goals are sometimes associated with better weight-loss outcomes. Furthermore, two studies showed that interventions designed to improve weight-loss outcomes by altering unrealistic goals resulted in more realistic weight-loss expectations but did not improve outcomes.”

Truth number 3: Large, rapid weight loss is associated with long-term weight-loss outcomes comparable with slow, gradual weight loss.

“Within weight-loss trials, more rapid and greater initial weight loss has been associated with lower body weight at the end of long-term follow-up. A meta-analysis of randomized, controlled trials that compared rapid weight loss (achieved with very-low-energy diets) with slower weight loss (achieved with low-energy diets —
i.e., 800 to 1200 kcal per day) at the end of short-term follow-up (<1 yr) and long-term follow-up (≥1 year) showed that, despite the association of very-low-energy diets with significantly greater weight loss at the end of short-term follow-up (16.1% of body weight lost, vs. 9.7% with lowenergy diets), there was no significant difference between the very-low-energy diets and low-energy diets with respect to weight loss at the end of long-term follow-up. Although it is not clear why some obese persons have a greater initial weight loss than others do, a recommendation to lose weight more slowly might interfere with the ultimate success of weight-loss efforts."

Additional research, published in the American Journal of Preventive Medicine, had this to say after they reviewed the habits and strategies of those who had lost weight and kept most of it off for 10 years …

…the two most noteworthy predictors were magnitude of initial weight loss and duration of weight loss. Participants with larger initial weight losses experienced slightly faster regain early in the follow-up period. Despite this, they maintained substantially larger weight loss over the 10-year follow-up period. Initial weight loss was highly correlated with lifetime maximum weight. Thus, the same finding is seen if participants are categorized according to maximum lifetime body weight; heavier participants tended to regain more quickly initially but maintained significantly greater weight losses throughout the 10 years.

What the authors are saying, in reviewing the 10+-year successes is even though some initial weight is regained by the biggest, fastest losers, what they regain back still leaves them in a better position over those who take the slow and steady approach.
Truth number 4: It is not all that important to assess the readiness of change for diet readiness in order to help patients who require weight-loss treatment.
Truth number 5: Physical-education classes, in their current form, do NOT play an important role in reducing or preventing childhood obesity.
Truth number 6: Breast feeding is NOT protective against obesity.
Truth number 7: A bout of sexual activity does NOT burn 100 to 300 calories for each participant. It’s more like 14 calories.
Several good sites online have done reviews of this study. If your interest is in truths 4-7 please do a Google search to your heart’s content. For my purposes and my average-student’s purposes I really felt truths 1-3 were most relevant.

Original Source: N Engl J Med 368;5