Continuing in my discussion of the obesity myths, presumptions and facts, published recently in the New England Journal of Medicine, today’s myth is about the rate of weight loss.
As the authors put it:
“Large, rapid weight loss is associated with poorer long-term weight outcomes than is slow, gradual weight loss.”
This “myth” is attributed to
“…a reaction to the adverse effects of nutritionally insufficient very-low-calorie diets (<800 kcal per day) in the 1960s; the belief has persisted, has been repeated in textbooks and recommendations from health authorities, and has been offered as a rule by dietitians.”
This reaction would be no surprise, as in those days, the very-low-calorie diets due to inadequate protein content (and perhaps a few other nutritional deficiencies) did result in rapid loss of lean tissue, thereby reducing metabolic rates beyond what may have been expected with a more gradual nutritionally balance weight loss.
In contrast, today’s low-calorie formula diets are generally high in protein and nutritionally balanced (except perhaps for fibre) and have in fact been shown in some cases to preserve lean body mass compared to simply eating less.
As regular reader of these pages may recall, I have previously written about situations where rapid weight loss with the use of low-caloric diets (900 Cal/day) may be indicated and in fact beneficial for patient management.
Nevertheless, as the authors point out, when comparing longer-term outcome data (a couple of years and beyond), it does not appear that people, who lose large amounts of weight rapidly have any less (or greater) chances of keeping weight off, than those who lose weight slowly.
Obviously, as with any diet, the ultimate question is really, whether or not patients can live on a restrictive caloric intake (and a rather high amount of physical activity) in the long-term.
As I recently pointed out in my discussion of the findings of the National Weight Control Registry, maintaining a significant amount of weight loss, is ongoing hard work and not everyone can be a Mark, Julie, Gertrude or Janice.
Thus, although one may well assume that the more radical changes required to precipitate faster weight loss are less likely to be sustainable than more moderate and gradual changes, we must recognise that the effort to keep a given amount of weight off is the same irrespective of whether this weight was lost fast or slow.