Excluding meat from your diet does not have to increase your appetite -- there are millions of vegetarians who are perfectly able to regulate their food intake without feeling deprived. Protein has been shown to have an effect on satiety, but only in higher-than-normal amounts. If your protein intake is typical, it probably is not affecting your appetite. Several studies have shown that getting up to 35 percent of your calories from lean protein may reduce your appetite, but meat is not the only source of protein.
Ketosis
According to a 2005 paper in "The American Journal of Clinical Nutrition," a diet that contains 30 to 40 percent protein may help to reduce hunger by triggering ketosis, a condition that results when your body's carbohydrate stores are depleted and you begin burning fat for fuel. Ketosis is the reason for the success of high-protein weight loss diets because it suppresses the appetite and may even produce feelings of nausea that may cause temporary food aversion. The paper also mentions a study that found that increasing protein intake at the expense of fat instead of carbohydrates produced the same effect, so ketosis is not be the only process at work.
Mechanism
A 2011 study in the journal "Obesity" found that a high-protein diet led to reduced hunger, especially at night and in the morning, and especially when participants ate three large meals versus six small ones. Another study, published in the "British Journal of Nutrition" that same year, tried to identify the mechanism by which protein decreases appetite, but the verdict is not yet in. Researchers suggested that an increased rate of gluconeogenesis during high protein intake may help keep blood glucose levels stable, but the study results found the two to be unrelated. Instead, it may be an increase of beta-hydroxybutyrate, a type of ketone -- which leads right back to the ketosis theory. Further research is needed before specific recommendations can be made.
Protein
Until the actual mechanism by which protein reduces hunger is known, it's best to keep your protein intake below 35 percent. Meat is not the only source of protein, so even vegetarians can use protein to eat less. Soy, whole grains and dairy products are good non-meat protein sources, and there is no evidence to suggest that these proteins affect the appetite any differently from animal proteins. Be sure to eat a wide variety of plant protein sources so you get the full complement of essential amino acids.
Hunger vs. Craving
It's not yet clear whether protein reduces actual hunger or simply cravings. True hunger is a physiological thing -- your stomach rumbles, and you may feel weak, lightheaded, or get a headache. This is caused by your body's internal sensors when your blood sugar drops and they sense fuel is running low. Cravings, on the other hand, are psychological -- they are the desire to eat, not the physical need. True hunger is satisfied by anything edible, while cravings are satisfied by a particular food or type of food. Cravings occur more often when the diet is restricted, and are usually aimed at the prohibited food.
References
- "The American Journal of Clinical Nutrition"; The Satiating Power of Protein -- A Key To Obesity Prevention?; Arne Astrup; July 2005
- EurekAlert: Higher-Protein Diets CanImprove Appetite Control and Satiety; July 11, 2011
- "British Journal of Nutrition"; Gluconeogenesis and Protein-Induced Satiety; Veldhorst MA, et al.; July 2011
Member Comments