Controlling Appetite: The Long-Term Battle Against Weight Loss with Peptides, Protein, and Other Factors
The good news is that PYY doesn't appear to cause resistance in overweight people like insulin does. The bad news is that attempts to create a PYY-based weight-loss drug have been unsuccessful, largely due to unacceptable side effects such as vomiting.
You can eat protein to naturally stimulate PYY, which is why I eat eggs and fish for breakfast (their high protein content makes me feel full, and compared to grains or baked goods, eggs and fish, which contain the same number of calories, keep me from feeling hungry for longer).
You can also improve PYY levels by eating more slowly. Food travels through your stomach, reaches your small intestine, and then stimulates those PYY cells-this process takes time. If you wolf down your food, you'll eat far more than you would eat leisurely. Try to eat at a table whenever possible, rather than eating while walking. Try to put down your knife and fork frequently during meals to give your PYY-producing cells ample time to react.
As I mentioned before, a frustrating thing happens when following a weight-loss diet: as you shed fat, your levels of the hunger hormone ghrelin rise, while appetite-suppressing hormones like PYY decrease. Your body wants to retain fat, thus hindering your shedding of it. This is an unfortunate remnant from a long time ago, when storing thick layers of fat was like depositing money in a bank-a crucial element for survival in times of scarcity.
The fact that the body seems very reluctant to give up its fat has led to some dogmatic assertions about weight loss diets, such as "95% of diets will fail" or "most people cannot lose weight and maintain their figure."
Although frequently cited, the "95%" figure is fabricated, as is the similar claim that "we only use 10% of our brains." I've always tried to find a credible theoretical basis for this assertion, but it simply doesn't exist.
Yes, many weight loss diets have failed, especially low-fat diets that have been heavily promoted for years. But some diets have a pretty good track record, such as the Mediterranean diet.
For various reasons, the Mediterranean diet is a diet I am very fond of (see my book "Intermittent Fasting: The Sugar-Free Diet"). People have conducted long-term studies on various diets based on the Mediterranean diet and found that although there is a slight rebound in weight after about 6 months of following the diet, if you stick to the diet for a year, you are very likely to maintain a good figure for many years to come [1].
A recent study at the University of Copenhagen confirmed this by observing the long-term effects of appetite hormones[2].
In this study, 20 healthy but obese individuals followed an 800-calorie-per-day diet for eight weeks. The volunteers lost an average of 13% of their body weight. They then continued with a year-long weight loss program that included psychological support and lifestyle interventions. Contrary to the myth of inevitable weight regain, they maintained their weight loss. Blood tests were conducted to measure their appetite hormone levels before and one year after the weight loss program.
Scientists discovered that the volunteers' levels of the hunger-inducing hormone ghrelin returned to normal, and their levels of the hunger-suppressing hormone PYY were also 36% higher than initially.
This study suggests that if you can maintain your weight loss for a period of time (perhaps up to a year), your body will eventually "accept" the new weight and consider it normal.
“At this point,” Dr. Torekoff of the University of Copenhagen points out, “the body no longer resists, but cooperates with you. This is good news for anyone who wants to lose weight.”
[1] Weight loss through a low-carbohydrate Mediterranean diet or a low-fat diet. Shai I et al., The New England Journal of Medicine, 2008
[2] Methods for successfully maintaining weight after weight loss include long-term dietary regulation targeting glycosaminoglycans (GLP-1) and tyrosinase (PYY 3-36). Lepsen, Lung ren, Holst et al., *European Journal of Endocrinology*, 2016