A team of 17 internationally recognized scientists published a paper supported by more than 169 journal references, proposing that the current obesity epidemic is not caused just by taking in too many calories (Am J Clin Nutr, September 13, 2021). They believe that obesity is caused primarily by hormonal changes brought on by eating refined carbohydrates and sugar-added foods.
These foods cause a high rise in blood sugar that markedly:
• increases insulin secretion that makes you hungrier (N Engl J Med, 1971;285(8):443-9), and
• decreases glucagon secretion that functions to make you feel full, so you keep on eating (Trends Endocrinol Metab, 2018;29(5):289-99).
Insulin also causes changes in metabolism that signal fat cells to store more fat (Obesity, 2020;28(11):2098-106). These studies do not recommend restricting all carbohydrates, just those that cause high rises in blood sugar (Science, May 7. 2021).
What Are Unrefined and Refined Carbohydrates?
Unrefined carbohydrates are parts of plants that have not been stripped of their other outer coatings, ground up and otherwise changed before you eat them: whole fruits, vegetables, un-ground whole grains, beans, nuts and other seeds. Refined carbohydrates are plant parts that have had basic components removed or have been ground into flour: all extracted sugars, bakery products, pastas, most dry breakfast cereals and so forth. Fruits can contain a lot of sugar, but they are considered unrefined because they have soluble fiber and antioxidants that markedly reduce the rise in blood sugar when you eat them (Exp Ther Med, Aug, 2016;12(2): 1232–1242)..
You Need Carbohydrates
Carbohydrates are usually the main source of energy for our bodies to function, while protein provides amino acids to grow and repair our cells. Carbohydrates are sugars in singles and combinations of up to millions of sugars bound together. Humans can absorb only single sugars. Most unrefined carbohydrates contain many sugars bound together, and we lack the intestinal enzymes to break them down.
Most of the carbohydrates in vegetables, unground whole grains, beans, nuts and other seeds cannot be absorbed from the upper intestinal tract so they pass all the way to the colon where bacteria do have the enzymes to ferment them and break them down to short chain fatty acids or SCFAs (Proc Nutr Soc, 2015;74:13-22). These byproducts of fermentation by bacteria in the colon cause good bacteria to grow in the colon, which reduce inflammation that contributes to heart attacks, diabetes, cancer, and obesity (World J Gastroenterol, 2011;17(12):1519-1528). They also lower high blood pressure, high blood sugar, and high cholesterol.
Evidence Linking Refined Carbohydrates and Obesity
Overweight people who eat mostly whole foods rather than processed foods can lose weight without counting calories or restricting portion sizes:
• A study from Stanford showed that restricting processed foods, particularly 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).
• A study from the University of Aberdeen showed that eating whole plants rather than refined plant foods, such as those made from flour or with added sugars, 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).
• What you eat may be far more important than how much you eat.
• Obesity increases risk for heart attacks, cancers, diabetes and premature death.
• Counting calories or trying to limit portion sizes have been repeatedly shown to fail to control weight in the long run.
• Studies on colon bacteria are showing that eating lots of unrefined carbohydrates from plants and avoiding refined carbohydrates, such as sugar-added foods and drinks and foods made from flour, can help people lose weight and keep it off.
• I recommend eating plenty of vegetables, beans, whole grains, nuts and other seeds, and whole fruits.
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe’s full bio.