Plants Release an Appetite-Suppressing Hormone

When you are trying to lose excess weight, eat lots of leafy green vegetables. Researchers at Imperial College in London found that high-fiber foods from plants help people lose weight by causing the intestines to release an appetite-suppressing gut hormone called PYY (Science Translational Medicine, June 19, 2024:16 (752)). This could save your life: the Center for Disease Control reports that more than 73 percent of North American adults are overweight (National Health Statistics Reports, June 14, 2021;158:1-19) and being overweight markedly increases a person’s risk for heart attacks, strokes, cancers and organ damage.

The researchers assigned 10 healthy volunteers to four days on each of three diets that contained:
• High-fiber whole foods, such as peas and carrots
• High-fiber foods with disrupted structures (mashed or blended)
• Low-fiber foods
All three diets contained the same number of calories and nutrients, but only the two high-fiber diets were fiber-matched at 46-47 grams daily, while the low-fiber diet contained 12.6 grams of daily fiber. Both of the high-fiber diets significantly increased PYY release, and those on the high-fiber diets had far less hunger two hours after their meals than those on the low-fiber diet.

More Ways Plants Help You to Lose Weight
Obesity is influenced by the types of bacteria in your colon, and we have known for almost twenty years that your eating habits may encourage the growth of fat-storing types of bacteria (Nature, 2006;444:1022–3). Many studies have shown that obese people have colon bacteria that are different from those who are skinny (Iran Biomed J, 2020;24:148–54; Current Opinion in Gastroenterology, 2010;26:5–11). Eating lots of high-fiber foods fosters the growth of healthful colon bacteria (Food Funct, Apr 2016;7(4):1788-96).

Fiber cannot be absorbed until it is broken down into its basic building blocks. You lack the intestinal enzymes to break down fiber, so it passes into the colon, the last five feet of your intestinal tract. There, colon bacteria break down soluble fiber into SCFAs (Short Chain Fatty Acids) that are absorbed into your bloodstream and help to control body fat by lowering high blood sugar, high insulin and other drivers of fat production. Soluble fiber also helps to lower high blood pressure.

Try to Restrict Highly Processed Foods
Overweight people who eat mostly whole foods rather than ultra-processed foods can lose weight without counting calories or restricting portion sizes. A study from Stanford showed that restricting processed foods, particularly those with added sugars and other refined carbohydrates, is more important for weight loss than going low-carb or low-fat (JAMA, Feb 18, 2018;319(7):667-679). This study showed that overweight people could lose weight if they follow a healthful diet based on whole foods, and restrict refined carbohydrates and other ultra-processed foods (BMJ, Sept 27, 2023;382:e0273939).

My Recommendations
If you are trying to lose weight and prefer not to use weight-loss drugs, try to increase your intake of plant foods, particularly leafy-green vegetables that are loaded with fiber. These foods result in the release of PYY, a gut hormone that helps to suppress hunger so you eat less. Also try to restrict foods that cause a high rise in blood sugar, which raises insulin and increase hunger:
• foods made from flour (bakery products, pasta, chips, crackers, many breakfast cereals)
• drinks with sugar in them (including fruit juices)
• foods that contain added sugars
• many other ultra-processed foods
Even if you are not trying to lose weight, I recommend eating this way to keep from gaining the ten or more pounds that most people add with each passing decade.