Losing weight is hard, but holding onto hard fought gains can be even harder. Weight regain is faced by almost all successful weight losers, resulting in the need to turn to yet another variation of the dieting, exercising and self-denial merry-go-round ride.
Weight regain is well described in the medical literature, but the reasons for it are not entirely clear. Plateauing of weight loss and a subsequent drop in motivation to keep up the changes in diet and exercise changes certainly play an important role.
Australian researchers have added a new piece to the puzzle of weight regain, by studying how the hormones that drive us to eat and make us feel full can change after a period of weight loss.
Published in the New England Journal of Medicine , researchers from Melbourne followed a small group of 50 overweight adults during a 10 week weight-loss program. The program involved a very-low-energy diet using a meal replacement product that provided them with just over 2000 kJ (500 Calories) each day. Clearly showing that kilojoules in do matter, such a severe energy reduced diet resulted in dramatic weight loss of an average of 13.5 kg in the participants.
At the start and end of the 10 week study and a further 12 months after this, the researchers measured the blood levels of 9 different hormones involved in appetite and hunger regulation.
By 10 weeks, there were significant changes in most of the hormones. Hormones involved in stimulating appetite and hunger increased, while those that help to blunt appetite and hunger decreased. Even though the hormone profile of the participants was primed to drive them to eat, continuing to adhere to the weight-loss program still kept the kilograms falling off as you would expect.
One year later, and well after the diet ended, much of the weight was regained. There were still significant differences in the levels of most of the hormones compared to the levels measured before weight loss started so the hormone profile was still tipped towards restoring weight back to its starting point.
What it all means
This research reinforces the theory that the body resists changes to a set weight it has become adapted to over time (called the settling point). One of the ways the body responds to weight loss is through changes in hormones that drive us to eat or make us feel full. Even with these mechanisms in place, it still requires a person to eat food to regain the weight.
Because many people have successfully maintained weight loss permanently, there still should be the motivation to lose weight and keep if off long-term which can help reset the body’s weight set point to a lower number on the dial.
Confused about the mixed soup of nutrition messages being stirred through the media? Tim maintains an active nutrition blog at www.thinkingnutrition.com.au  where you'll find the latest nutrition research and controversies discussed in straight forward language, distilling out what you need to know for your better health.