The rate of obesity in the U.S. is worse now than it has ever been: 43 percent are obese, 10 percent are morbidly obese, and childhood obesity rates have tripled from five percent in the early 1970s to more than 19 percent now (USAfacts.org, April 26, 2023). If you are trying to lose weight, or to avoid gaining weight, work on:
• picking the right foods,
• preparing your foods so you absorb fewer calories, and
• moving about before and after you eat.
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 demonstrates that overweight people can lose weight if they follow a healthful diet based on whole foods and restrict refined carbohydrates and other processed foods.
Limit or avoid foods made from flour, foods with added sugars, sugar-sweetened beverages, refined grains and starchy vegetables. Consume more whole grains, non-starchy vegetables and whole fruits (BMJ, Sept 27, 2023;382:e0273939). Fiber and other resistant starches contain long chains of sugars that cannot release their end sugars, so they are not absorbed in your small intestines and pass on into your colon. Bacteria in your colon ferment some of these carbohydrates and convert them into Short Chain Fatty Acids (SCFAs) that are absorbed into the bloodstream where they lower high blood sugar, insulin, cholesterol, blood pressure and inflammation (Am J Clin Nutr, 2000;72(6):1461-68). The carbohydrates that are not fermented or eaten by the good bacteria in your colon pass out undigested, adding bulk to your stool and helping to prevent constipation.
The most healthful carbohydrates are those left where nature puts them: in vegetables, fruits, whole grains, beans, nuts and other seeds. The harmful carbohydrates are usually found in processed foods made with refined carbohydrates (flour, white rice, milled corn, potato starch and so forth), and all extracted sugars including fruit juices.
Eating whole plant parts rather than refined plant foods results in far more healthful intestinal bacteria than a diet with high protein or added amino acids (European Journal of Nutrition, February 20, 2018:1-12). The soluble fiber in unrefined carbohydrates is fermented by bacteria in the colon into healthful breakdown products that have been shown in other studies to help control weight and promote good health.
Plants Help You Lose Weight
A plant-based diet can help you lose excess 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). Eat lots of fruits, vegetables, whole grains, beans, nuts and other seeds, which are high in fiber that fosters the healthful colon bacteria (Food Funct, Apr 2016;7(4):1788-96).
Before food can be absorbed from your intestines into your bloodstream, it must be broken down into basic building blocks. Since you lack the intestinal enzymes to break down fiber into its building blocks of basic sugars, you do not absorb fiber in your upper intestines. Fiber passes through your intestines into your colon where soluble fiber which is readily fermented by enzymes produced by bacteria in your colon, so its breakdown products can be absorbed in your colon. Soluble fiber does all sorts of good things for you:
• It helps to draw water into your stomach to delay emptying and keep your stomach full, so it can decrease the amount of food that you eat
• It helps to lower blood sugar and insulin levels by slowing the rate at which your body absorbs sugar from your intestines.
• It binds to sugars and starches, preventing them from being absorbed in the intestines so they pass to the colon. There bacteria break down the soluble fiber, releasing the sugars so they can be absorbed. This delayed absorption markedly reduces the rise in blood sugar that follows eating fruits, vegetables and grains
Limit How Much Meat You Eat
Eating meat causes a high rise in insulin because insulin’s main function is to drive sugar, fat and amino acids, the building blocks of protein, into your liver. Meat is full of protein and usually contains lots of fat. An obese person’s liver is likely to rapidly convert protein and fat to sugar (Diabetes Educ, Nov-Dec 1997;23(6):643-6, 648, 650-1). This is called gluconeogenesis. Eating lots of protein can also increase diabetes risk by adding fat to the liver, and harm people who are already diabetic by increasing the rate of gluconeogenesis. See Red Meat Associated with Increased Risk for Diabetes
Eat More Uncooked Fresh Foods
Cooking increases the calories absorbed from the food, in studies on people and on mice (PNAS, November 7, 2011;108(48):19199-19203). For example, cooking sweet potatoes increases calorie absorption by more than 30 percent over raw sweet potatoes.
Avoid Eating at Night
Resting muscles draw almost no sugar from the bloodstream, while contracting muscles draw sugar from the bloodstream without even needing insulin. The harder you exercise, the more sugar muscles pull out of the bloodstream. This effect is maximal during intense exercise, diminishes rapidly one hour after you finish exercising and disappears completely after about 17 hours. If you eat before you exercise or within an hour after you finish exercising, your muscles are far more sensitive to insulin and can draw sugar far more rapidly from the bloodstream.
Move about throughout the day, and exercise as many days as you can. Do not go to bed shortly after you eat. Contracting your muscles before or after you eat helps to prevent a high rise in blood sugar when you eat. A high rise in blood sugar causes sugar to be converted to fatty triglycerides which are then stored in your body as excess fat.
If you are trying to lose weight or are diabetic or pre-diabetic, I recommend that you restrict all foods that cause a high rise in blood sugar:
• foods made from flour (such as bakery products, pasta, chips, crackers, many breakfast cereals)
• all drinks with sugar in them (including fruit juices)
• all foods that contain added sugars
• many other ultra-processed foods
Even if you are not trying to lose weight, I recommend limiting these foods to keep from gaining the ten or more pounds that most people add with each passing decade.