I often joke that the easiest way to gain 25 lbs is to lose 20!
Unfortunately, this may not be much of a joke, as there is mounting evidence that intentional weight loss may indeed be an important driver of long-term weigh gain.
New evidence in support of this hypothesis comes from a Finnish twin study by Kirsi Pietiläinen and colleagues from the University of Helsinki, published in the latest issue of the International Journal of Obesity.
Subjects included 4129 individual twins from the population-based FinnTwin16 study (90% of twins born in Finland 1975–1979). Weight and height were obtained from longitudinal surveys at 16, 17, 18 and 25 years and examined in relationship to the number of lifetime intentional weight loss (IWL) episodes of more than 5 kg at 25 years.
A single IWL episode increased the risk of becoming overweight by age 25 almost three-fold in women and two-fold in men. In fact, women who reported two or more IWL episodes had an even higher (5-fold increased) risk of becoming overweight at age 25.
In monozygous twin pairs discordant for IWL, co-twins with at least one IWL were 0.4 BMI units heavier at 25 years than their non-dieting co-twins despite no differences in baseline BMI levels.
Similarly, in dizygous pairs, co-twins with IWLs gained progressively more weight than non-dieting co-twins (BMI difference 1.7 units at 16 years and 2.2 units at 25 years).
These findings not only confirm previous studies that dieters may be more prone to future weight gain but also provide evidence that, this obesogenic effect of dieting is apparently independent of genetic factors.
All the more reason to warn against the widespread obsession with ‘cosmetic’ weight loss — as I have said before, all weight loss attempts should be medically indicated and anyone attempting to lose weight needs to be warned that they may in fact be increasing their long term risk of becoming (even more) overweight or obese.
On the other hand, in cases where weight loss is indeed medically indicated, considerable effort and long-term follow up will be required to prevent relapse – not only is weight loss not a ‘cure’ for obesity but, in many cases, losing weight can actually make the problem worse!
Imagine if all diet and weight loss products and programs had to come with aclear ‘warning’ that use of these products or programs may increase the risk of obesity!
Clearly something for the weight-loss industry and the many self-appointed weight-loss ‘gurus’ to chew on.