Late Night Eating And Weight Loss

The Study

Does eating food late at night make it harder to lose weight? This cross-sectional study was designed to shed light on this hypothesis. Over 3,000 subjects from a weight loss program in Spain had the midpoint of the time between breakfast and dinner calculated. The group was divided into early eaters and late night eaters. The results were fascinating:

-For starters, there were no significant differences between late and early eaters in energy intake or physical activity.

=Late night eaters had a higher BMI, body fat and waist circumference than early eaters.

-Late night eater’s rate of weight loss was 80 grams less per week compared to the early eaters. This difference was statistically significant and added up to over 3 pounds less weight lost during the 5 month intervention.

-Late night eaters had higher triglycerides and lower insulin sensitivity when compared to early eaters. American Journal of Clinical Nutrition 2021 113:154-61.

Take Home Message

I have been telling my clients for years to stop eating after 8:00 PM if they are trying to lose weight. While I have found this to be anecdotally important, there is not a ton of research to back this up. This study, although a weaker form of research (cross-sectional studies lack temporality and cannot determine causation) does provide some evidence that there may be something to this. Some potential mechanisms include:

-Late eating simply adds extra calories.

-Our metabolism may slow down at night, so more of what we eat is converted to fat.

-The thermic effect of food is lower at night.

-Late night snacking is generally of poor nutritional quality. High glycemic carbs like chips and cookies promote weight gain through their impact on your blood sugar.

Either way, it is a good idea to stop eating by 8:00 PM if weight loss is your goal.