For clients hoping to start the New Year with weight loss, speak to the science behind satiety to set them up for long term success. By framing both diet and exercise changes as additions, rather than eliminations or restrictions, clients are apt to stick to a healthier lifestyle long after January ends.
- Effectively explain the science behind hunger and satiety, and how they relate to weight management.
- Learn which macronutrients contribute to satiety.
- Identify which foods provide enhanced fullness, while providing nutrient dense calories for performance.
No matter what diet you or your clients champion, the buzz in your training facility this time of year undoubtedly revolves around weight loss, resolutions and SMART goal setting. As the library of research on physiology behind hunger and fullness grows, you can start to impart suggestions for small changes to your clients.
For normal eaters, satiety occurs at the end of a meal, and is the cumulative effect of several inhibitory signals—sensory, cognitive, digestive and hormonal—encouraging you to stop eating (Bellisle et al., 2012). Sensory and cognitive cues come mostly from the environment. Digestive cues depend on the rate of gastric emptying and how much the meal stretches the lining of the stomach.
Hormones don’t just make you moody—GI hormones are involved in bringing on sensations of both hunger and fullness, as well as enhancing or slowing gastric emptying. The big players are ghrelin, PYY 3-36, and glucogen-like poly-peptide 1 (GLP -1), although there are over 100 hormones involved in digestion.
Ghrelin is a neuropeptide that sends the “I’m hungry!” message. PYY 3-36 is a hormone that signals appetite suppression. Cholescystokinin (CCK), GLP-1, oxyntomodulin, pancreatic polypeptide and gastrin-releasing polypeptide all are triggers to increase satiety (Mahan & Escott-Stump, 2008).
Ideally, this meal keeps you full for several hours, before it’s time to eat again. You can cognitively override these satiety cues, and chronic yo-yo dieters may have trouble sensing these hunger and fullness cues clearly. For those hoping to manage their weight, adding in foods that help to promote satiety can be an effective strategy.
Role of Macronutrients: Protein, Fat and Carbohydrates
Each type of macronutrient is metabolized by your body through a different chain of reactions involving neuropeptides, hormones and enzymes. Protein (amino acids) have the greatest effect on fullness. After protein is consumed, GLP-1, PYY 3-36, and glucagon are increased. Ghrelin is also decreased, and feelings of fullness increase. This is a dose dependant reaction—one of the reasons protein is often emphasized in weight management (Belza et al., 2013).
While fat fear continues to reign, fat is very satisfying—for taste buds and satiety hormones. GLP-1 and CCK is also stimulated by fat rich meals (Mahan & Escott-Stump, 2008). Because fat takes a while to break down into individual fatty acids, the rate of gastric emptying is slower, keeping you fuller for longer. Fats from nuts, seeds and avocado break down slower than more refined oils.
Compared to low glycemic whole grains, carbohydrates with a high glycemic load are likely to result in an energy spike then a crash, which leaves you hungrier than ever (Chang et al., 2012). Encourage your clients to look for minimally-refined sources of carbohydrates—including starchy vegetables—that are rich in fiber. Soluble fibers are particularly satiating, since they slow down the transit time of food (Mahan & Escott-Stump, 2008). The volume of carbohydrate also matters— nutrient dense whole grains (like popcorn) keep you fuller than calorie-dense refined carbohydrates (like potato chips) (Nguyen et al., 2012).
Micronutrients and Cravings
Cravings come from many places, and are often connected to emotions. A client may complain that they crave chocolate whenever they are bored or lonely. Or may only succumb to cravings on the weekends when they are socializing. Ensure that the craving is not rooted in a micronutrient deficiency by adding in extra servings of fruits and vegetables. If your client is on a restricted diet, a multivitamin supplement can be beneficial.
Add Nutrient Dense Whole Foods
Most diets and lifestyle changes focus on avoidance and restriction. Unfortunately, this can leave your clients feeling hungrier and more fatigued than ever. In fact, diets are the top predictors of future weight gain (Lowe, Doshi, Katterman, & Feig, 2013). Fad diets and weight cycling can have many ill effects on clients, including reduced bone mass and psychological stress (Bacon & Aphrmor, 2010). Instead of talking to clients about what to subtract from their diet, encourage them to add nutrient dense foods that promote satiety.
Plant-based sources of protein, fat and fiber contribute the volume and macronutrients that help you feel full, while being lower in calories than their more processed animal-based counterparts. Your clients may be unfamiliar with plant-based proteins and healthy fats, so encourage them to add a serving of beans, nuts, seeds, tofu, tempeh, or a multisource protein blend. Avocados, nuts and seeds are also excellent sources of unsaturated fatty acids. Flax, chia and sacha inchi seeds are plant-based sources of Omega-3s, as well as fiber, vitamins and minerals. Challenge your clients to add an extra serving of veggies to one meal, to see the difference in their hunger level afterward.
For more tips on how plant-based nutrition can help promote satiety and weight management, visit Thrive Forward—a free, online wellness platform. Share it forward by giving a client a new recipe, or encourage them to record a week of their meals (along with their hunger and fullness) in the meal logging handout provided.
Bellisle, F et al. (2012). Sweetness, Satiation, and Satiety. The Journal of Nutrition 142:6. 1149S-1154S. Retrieved from: http://jn.nutrition.org/content/142/6/1149S.long
Mahan, L.K., Escott-Stump, S. (2008). Krause’s Food and Nutrition Therapy. Saunders Elsevier. 12th ed.
Belza, A., et al. (2013). Contribution of gastroenteropancreatic appetite hormones to protein-induced satiety. American Journal of Clinical Nutrition. 97(5):980-9.
Chang, K.T., et al. (2012). Low glycemic load experimental diet more satiating than high glycemic load diet. Nutrition and Cancer. 64(5):666-73. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3762696/
Nguyen, V., et al. (2012). Popcorn is more satiating than potato chips in normal-weight adults. Nutrition Journal. 11: 71. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3502142/
Lowe, M.R., Doshi, S.P., Katterman, S.N., Feig, EH. (2013). Dieting and restrained eating as future predictors of weight gain. Frontiers of Psychology. 4;577. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3759019/
Bacon, L., Aphrmor, L. (2010). Weight Science: Evaluating the Evidence for a Paradigm Shift. Nutrition Journal. 10;9. Retrieved from: http://www.nutritionj.com/content/10/1/9