In a a recent study on mice that compared lifelong obesity against the ups and downs of yo-yo dieting, it was found that trying to lose weight, even by yo-yo dieting, is better than remaining at an unhealthy weight.
In the study, 3 groups of mice each received one dietary treatment for their whole lives - either low fat, high fat or a yo-yo diet with fluctuating periods of low and high fat. Throughout the study, their body weight, body fat and blood glucose levels among other indicators were measured. As expected, those mice on the yo-yo diet had large fluctuations in their health measures but the ones on the lifelong high fat diet slowly but surely progressed towards diabetes and other chronic diseases related to obesity and a poor diet. The researchers were surprised to find that the mice on the yo-yo diet had a similar lifespan to those on the low-fat diet and they lived 35% longer than those on the high-fat diet.
So, while it is true that following a stable, healthy diet for life is the most sound dietary option, the researchers suggest that the perils of yo-yo dieting may be overemphasized. According to the researchers, "The fear of negative health consequences due to weight cycling may be overemphasized. From our study, it appears that it is better to continue to encourage weight loss regardless of the number of attempts and failures." So ultimately, any attempt at better health is better than none.