Philip J. Goscienski, M.D.
You probably know someone who has gone through weight-cycling, known popularly as yo-yo dieting. The steady rise in obesity that now affects more than a third of the adult population has spawned plenty of weight-loss plans but few of them work. The result is a large number of people who have gone through periods of losing and regaining weight, sometimes in staggering amounts of a hundred pounds or more. Some nutrition scientists maintain that yo-yo dieting doesn't do any harm, basing their claim on a lack of sufficient studies. My gut feeling — pardon the pun — is that they are wrong.
Our Stone Age ancestors undoubtedly went through periods of food abundance and scarcity but their largely plant-based, calorie-sparse diet and their physically-demanding lifestyle made obesity unlikely even in the best of times. Gaining and losing a few pounds now and then doesn't matter; large swings probably do.
Rapid weight loss of more than two pounds a week is associated with gallbladder disease. Weight-cycling increases the risk and the greater the swings, the greater the likelihood of developing gallstones. Men who lost and regained 20 or more pounds in the course of their attempts to lose weight were 76 percent more likely to have gallstones than men whose weight remained constant. In that large study of more than 25,000 participants, those who underwent more than one cycle doubled their risk.
When food intake is significantly reduced the bile in the gallbladder is more likely to become sludge-like and to form stones. Many people with gallstones get through life with no problems. However when a stone becomes lodged in one of the channels that delivers bile to the intestine to aid in digestion it leads to obstruction, inflammation and the need for surgery.
There is disagreement on whether it's harder to lose weight with subsequent attempts. When rats were deprived of food, refed and fasted again it took twice as long for the animals to lose the same amount of weight. Rats are obviously not the same as humans, but rats don't cheat!
Obesity brings so many risks of chronic disease and early death that it makes sense to lose weight. The best method is simple but not easy: eliminate refined flour and sugar, especially soft drinks; eat more green leafy vegetables; get at least one hour a day of moderately intense exercise. And you can do these things forever -- safely.
Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at firstname.lastname@example.org.