Most of you already know that weight gain, diabetes and heart attacks are associated with eating pro-inflammatory foods such as mammal meat, sugar-added foods and fried foods. However, you may not know that people who eat their meals very fast (an average of less than six minutes), snack after supper just before going to sleep, or who skip breakfast, are also at increased risk for these three conditions (Scientific Reports, June 3, 2019;9(8210); Clinical Nutrition, April 2013;32(2):23-25; Nutrients, 2019 Jan; 11(1): 83).
• People who eat fast are about 60 percent more likely to have the high blood triglyceride levels that come from having high blood sugar levels after meals. Researchers used a self-monitoring wearable device to demonstrate that eating hard foods and restricting processed foods that are soft caused normal weight people to eat more slowly so they ate less food (Am J Clin Nutr, 2022 Jul; 116(1): 244–254).
• A seven-year, self-reported speed-of-eating study of middle-aged Japanese men found that faster eating was associated with increased weight gain and becoming diabetic (Clinical Science, Nov 2012;61(11):1566-1571).
• Avoiding soft processed foods and eating meals slowly reduced hunger and food intake (Appetite, May 1, 2023;184:106505).
• Stomach X rays of competitive speed eaters showed that their stomachs were enormous flaccid sacs capable of accommodating huge amounts of food, and they were at increased risk for nausea, vomiting, stomach paralysis and morbid obesity (American J Roentgenology, September 2007;189(3)).
How Eating Very Fast May Harm You
When your stomach is empty, it produces a hormone called ghrelin that makes you hungry. When you eat, your stomach fills up with food, since no solid food is allowed to pass from your stomach into your intestines. This stretches your stomach so it stops producing the hormone called ghrelin, so you are less hungry and stop eating. However, it usually takes more than 20 minutes for ghrelin to quiet down your hunger center in your brain. Ghrelin suppression after they ate a meal was far quicker and greater in the slow-eating group than the fast-eating group. Three hours after eating, the slow eaters had consumed an average of 25 percent less energy from snacks (Nutrients, Jan 2019;11(1):50). So the faster you eat, the more food is allowed to accumulate in your stomach before the ghrelin signal has a chance to take effect. Thus fast eating can cause you to eat more food and have a higher rise in blood sugar, which is converted to triglycerides that are used to make more VLDL cholesterol molecules, and you get a higher rise in blood cholesterol levels. Also, this delay in time for you to feel as though you have a full stomach can cause you to eat more food. It takes longer for your fat cells to fill with fat and release another hormone called leptin that makes you feel full so you stop eating. That is why fast eaters usually take in more calories and therefore are fatter and have higher blood sugar levels to increase diabetes risk, which increases risk for a heart attack. Another study showed that obesity is associated wth increased stomach size, faster stomach emptying for solids and liquids and higher after-eating levels of glucagon-like peptide 1 that makes you hungry, so you eat more food before you feel full and have a larger waist circumference (Gastroenterology, March 2015;148(3):537-546.e4).
Time of Eating Also Affects Weight Gain and Risk for Diabetes and Heart Attacks
• Having the largest meal early in the day and eating most of your daily food during lunch help to prevent excess weight gain (Clinical Nutrition, April 2024;60:179-186).
• Eating a large breakfast and a small dinner is associated with reduced risk for high blood sugar levels in diabetics (Diabetologia, Mar 2015;88:912-919).
• A review of 20 studies found that overweight people who stopped eating in the evening for at least four weeks had lower fasting blood sugars, insulin and HbA1c (Reviews in Endocrine and Metabolic Disorders, Nov 22, 2023; 25:325-337). HbA1c is a measure of cell damage from high blood sugar levels.
• The French NutriNet-Sante study found that eating dinner late in the evening is associated with increased risk for both heart attacks and strokes (Nature Communications, Dec 2023;14(7899)). Having a first meal for the day (breakfast or lunch) late in the morning also increased risk. The researchers found that each hour of delaying the first meal of the day after 8:00 AM was associated with increased risk for both heart attacks and strokes. They recommended eating both early dinners and early breakfasts.
Don’t Eat and Go to Bed
• Skiping breakfast has been associated with overweight and obesity (Obes Res Clin Pract, 2020;14:1-8) and increased risk for a heart attack (Clin Nutr, 2020;39:2982-2988) and diabetes (J Nutr, 2019;149:106-113).
• Eating just before going to bed at night was associated with increased heart attack risk (J Am Heart Assoc, 2020;9:e016455), obesity, high cholesterol and diabetes in women (BMC Public Health, 2018;18:1-12) and heart attacks (Circulation, 2013;128:337-343).
• Eating late breakfasts tends to make longer overnight fasts so you may feel hungrier later on in the day, leading to higher food intake and increased insulin production. Skipping breakfast has also been associated with higher morning blood pressure and cholesterol levels (J Nutr Sci, Nov 2014; 3: e56).
Why Late Dinners are Less Healthful
Eating dinner just before you go to bed causes higher rises in blood sugar levels and increased amounts of fat to be deposited in fat cells while you are sleeping. Resting muscles draw almost no sugar from the bloodstream and what little they do remove from the bloodstream requires insulin (Sports Medicine, Feb 2, 2018;1-13:), while contracting muscles pull sugar from the bloodstream and don’t even need insulin to do so (Diabetes Research and Clinical Practice, Sept 2007;77(3):S87-S91). If you do not move around and contract your muscles after eating, you increase risk for high blood sugar levels.
• You burn the lowest amount of calories when you sleep. When you go to sleep after eating, you burn fewer calories from that food so more of it is stored as fat (Metabolism, 2009;58(7):920-926). Several studies show that blood sugar levels respond best to insulin during the day and worst at night (Nat Rev Endocrinol, 2019;15(2):75-89).
• Cortisol levels are higher during sleep and raise blood sugar levels by blocking the effects of insulin (Ann NY Acad Sci, 2017;1391(1):20-34).
• Changing the evening mealtime of non-obese men from 6:00 PM to 10:00 PM significantly increased their markers for becoming obese and developing diabetes (J Clin Endocrinol Metab, Aug 1, 2020;105(8):2789-2802). They had higher blood sugar, higher insulin, higher cortisol levels, and reduced ability to remove and use fat from their cells. These are all major risk factors for obesity.
My Recommendations
The least healthful time to eat is just before you go to bed, and the most healthful times to eat are before you exercise or within an hour after you finish exercising (Appetite, 2013 Jan;60(1):246-251). Exercising after eating causes contracting muscles to pull sugar from the bloodstream, which helps to prevent high rises in blood sugar. Eating within an hour after exercising also helps to prevent a high rise in blood sugar. Your muscles can extract sugar from the bloodstream maximally without needing insulin for about an hour after you finish exercising, but this ability is then gradually lost over about 17 hours (J Appl Physiol, 2005;8750-7587). Also, the faster you eat, the more calories you are likely to take in, which increases your chances of gaining weight.
