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 followed 103,389 people, average age 42.6, for 7.2 years, during which time there were 2036 cases of heart disease, 988 cases of strokes, and 1071 cases of heart attacks, angina and heart stents. The researchers found that each hour of delaying dinner after 5 PM was associated with a 7 percent increased risk for a stroke, and that eating dinner after 9 PM was associated with a 28 percent increased risk for a heart attack, compared to eating before 8 PM. They also found that each hour of delaying the first meal of the day after 8 AM was associated with increased risk for both heart attacks and strokes. The authors recommend eating both early dinners and early breakfasts.
Other Studies have Shown Similar Results
• Skipping breakfast has been associated with overweight and obesity (Obes Res Clin Pract, 2020;14:1-8), 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 high 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 prevents 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 or until you contract your muscles again (J Appl Physiol, 2005;8750-7587).
