Flavour of the Week

Post-Dieting Syndrome


We have all seen or personally experienced the weight relapse phenomenon – despite best efforts after significant weight loss, slowly but surely the weight creeps back up and may even surpass the initial weight. This begs the question: Why is weight maintenance so difficult, often even more so than the weight loss itself? Post-Dieting Syndrome, where the body “compensates” for weight loss by increasing appetite and decreasing satiety, may play an important role in weight regain.

Research now suggests that weight regain may not simply be a matter of poor self-discipline or a lack of willpower, but a biological perfect storm whereby the body actually fights against weight maintenance and promotes weight regain. But how exactly is does this “Post-Dieting Syndrome” sabotage weight maintenance? And what, if anything, can be done to fight back?

I recently attended a session on “Reducing the Burden of Obesity: A Role for Nutrition Therapy” presented by University of Calgary researcher and dietitian, Dr. Raylene Reimer. The session focused on novel, non-pharmacologic weight maintenance strategies and their potential in staving off weight gain and the so-called Post Dieting Syndrome.

While many external factors such as time of day, habit and stress play a role in when and how much we eat, we often forget about the powerful biological cues that drive appetite, namely hormones like ghrelin and peptide YY (also called PYY).

  • Ghrelin can be viewed as the “green light” hormone as it stimulates appetite and peaks before a meal.
  • PYY is a “red light” hormone that triggers satiety and turns off appetite.

The delicate balance of these hormones is crucial for weight maintenance and appears to be altered in those who are overweight and obese (1). Changes in these hormonal signals, as a result of weight loss, are also well-documented: ghrelin secretion increases and PYY release decreases. The imbalance in the satiety hormones effectively increases appetite while decreasing satiety, thus promoting weight gain (2).

Sumithran et al. (3) made headlines in late 2011 with research suggesting that these hormonal changes do not immediately disappear either; even at 1 year post-weight loss, appetite and satiety hormone levels were significantly different in comparison to baseline, as was perceived hunger.

All is not lost – there is hope! While Post-Dieting Syndrome is a physiological response that may promote weight relapse, maintaining weight loss is possible – you can fight and win! So, what boosts PYY and suppresses ghrelin, effectively countering the appetite increases that may accompany initial weight loss? Why exercise and diet, of course!

  • Physical activity.While impact of exercise on ghrelin is equivocal in the literature, PYY secretion seems to increase as a result of aerobic exercise and resistance training, helping to explain why people often experience a reduced appetite after exercise (4). Whether these exercise-induced changes in hormonal regulation of appetite influence subsequent food intake and weight maintenance, especially over the long-term, remains to be seen.
    Interestingly, a recent study compared hormonal responses to an energy deficit due to either caloric restriction or increased exercise and found that ghrelin and PYY compensation did not occur with physical activity, only caloric restriction (5). The study was small and used healthy adults but suggests that exercise may have a role in attenuating Post-Dieting Syndrome.
  • Dietary fibre. A 12-week randomized trial providing a 7 g dose of oligofructose (a prebiotic fiber) before breakfast, lunch and dinner showed great promise. In overweight and obese adults, the prebiotic fibre suppressed ghrelin and increased PYY levels. The fibre treatment group also  experienced modest weight loss, whereas the placebo group experienced weight gain. Furthermore, the majority of the weight loss was fat not muscle. Self-reported caloric intake was also significantly lower in the treatment group, though perceived appetite was not (6).
    A recent review of the literature supports these findings: dietary fibre promotes satiety, improves appetite regulation and has modest benefits with respect to weight loss (7).
  • Bariatric surgery. Interestingly, weight loss via bariatic surgery does not seem to have the same effects on appetite hormones as dieting. In fact, PYY secretion appears to be increased in the months following bariatic surgery, particularly after Roux-En-Y gastric bypass (8,9).

No Baloney’s advice. Don’t give up! In the most simplistic terms, weight gain occurs when fullness cues are overridden or hunger cues are ignored – so it’s time to get back in touch with those internal cues!

In honour of the just-passed No Diet Day on May 6th, we suggest halting the steady weight creep of adulthood by listening to what your body tells you – eat when you are hungry (i.e., don’t skip meal!) but stop eating when you are no longer hungry, which is very different than being full. Blindfold yourself and see how much you eat!

If you have recently lost weight, the importance of physical activity cannot be overstated – if you want to achieve and maintain change, it cannot just be about caloric restriction. If you are struggling with appetite at meals, try a pre-meal “cocktail” involving soluble fibre (like Benefibre®) mixed in a big glass of water to help promote appetite control.

We leave you with three words: hara hachi bu. Okinawans have the longest life and health expectancy on earth – The Okinawa Centarian Study is devoted solely to the study of those over 100 years old! The Okinawan practice of “hara hachi bu”, loosely translated as “eat until you are 80% full”, is thought to be a large part of their longevity. Pretty good advice that obviously pays off!

References:

  1. Karra E, Batterham RL. The role of gut hormones in the regulation of body weight and energy homeostasis. Mol Cell Endocrinol 2010; 316:120-8.
  2. Adams CE, Greenway FL, Brantley PJ. Lifestyle factors and ghrelin: critical review and implications for weight loss maintenance. Obes Rev 2011; 12:e211-8.
  3. Sumithran P, Prendergast LA, Delbridge E, Purcell K, Shulkes A, Kriketos A, Proietto J. Long-term persistence of hormonal adaptations to weight loss. N Engl J Med 2011; 365:1597-604.
  4. Li B, et al. Effects of exercise on the levels of peptide YY and ghrelin. Exp Clin Endocrinol Diabetes 2011; 119:163-6.
  5. King JA, et al. Differential acylated ghrelin, peptide YY3-36, appetite, and food intake responses to equivalent energy deficits created by exercise and food restriction. J Clin Endocrinol Metab 2011; 96:1114-21.
  6. Parnell JA, Reimer RA. Weight loss during oligofructose supplementation is associated with decreased ghrelin and increased peptide YY in overweight and obese adults. Am J Clin Nutr 2009; 89:1751-9.
  7. Wanders AJ, et al. Effects of dietary fibre on subjective appetite, energy intake and body weight: a systematic review of randomized controlled trials. Obes Rev 2011; 12:724-39.
  8. Valderas JP, et al. Medical and surgical treatments for obesity have opposite effects on peptide YY and appetite: a prospective study controlled for weight loss. J Clin Endocrinol Metab 2010;95:1069-75.
  9. Ochner CN, et al. Changes in neurohormonal gut peptides following bariatric surgery. Int J Obes (Lond) 2011; 35:153-66.
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2 thoughts on “Post-Dieting Syndrome

  1. Pingback: “The Biggest Loser” and a Culture of Weight Bias | No Baloney

  2. Pingback: TGIF | No Baloney

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