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Food for Thought Food for Thought

Does Eating Late Make You Gain Weight?

November 05, 2013

By Julia Luksha, B.S.
Brigham and Women's Hospital

For decades, eating late at night has been associated with weight gain. Remember the saying "Eat breakfast like a king, lunch like a prince and dinner like a pauper"? Is it true? 

Recent studies in both animals and humans are helping us get to the bottom of this. While the results are not unanimous, most studies show that eating late in the day will, in fact, contribute to weight gain and other potential health problems.

The latest study on this topic was published this year in Obesity. Researchers found that eating a big breakfast and a small dinner is better for weight loss than eating a small breakfast and a large dinner.  

Ninety-three women with metabolic syndrome participated in this study. They were randomly assigned to different diets. Group 1 ate a 700-calorie breakfast, 500-calorie lunch and 200-calorie dinner.  In contrast, Group 2 ate a 200-calorie breakfast, 500-calorie lunch and 700-calorie dinner. After 12 weeks, the researchers measured the weight loss in both groups. Women in Group 1 lost significantly more weight than women in Group 2.  

The researchers explain that the weight loss in Group 1 may be due to decreased levels of the hormone ghrelin. It increased the sense of fullness (satiety) from breakfast. Ghrelin stimulates appetite.  The women in Group 1 also had lower insulin, glucose and lipid levels, which shows that this eating pattern benefits overall health, as well. 

The study also suggests another factor that influences weight gain: the body's circadian rhythm or sleep-wake cycle. Your circadian rhythm is the 24-hour cycle during which the body carries out biological processes, such as the release of hormones. This study suggests that the time of day we eat affects how our body processes food. 

A recent study by Steven Shea and his colleagues at Brigham and Women's Hospital and Harvard Medical School found that the body's circadian rhythm actually increases hunger in the evenings. This is most likely contributing to the obesity epidemic in our country today.  And several other studies show that:

  • Eating late at night is associated with increased body mass index.
  • A disruption in circadian rhythm, as seen in night shift workers, increases a person's risk for obesity, diabetes and cardiovascular disease. 

These findings show that our circadian rhythms play a role in energy metabolism, weight regulation and overall health.

Sleep duration is also an aspect of weight loss that is closely tied to the body's circadian rhythm. A study by Shahrad Taheri and his colleagues at Stanford University found that less sleep interrupts our body's circadian rhythm. And lack of sleep was associated with a higher body mass index, an increase of ghrelin and a decrease of leptin. (Leptin is a hormone that suppresses appetite.) Consequently, people who get at least eight hours of sleep have a smaller appetite than those who get five hours of sleep.

Another study by Orfeu Buxton and his colleagues explored the effect of prolonged sleep restriction on metabolism in humans. They found that long-term sleep restriction slows metabolic rate and decreases insulin production, which contributes to the development of diabetes.

The problem with late night eating is that most people tend to overeat at this time. They eat out of boredom, or fail to adjust their daytime calories to allow for a nighttime snack. As a result, nighttime snackers are more likely to develop unhealthy eating habits.  This can lead to weight gain.

Timing is just one piece of the weight-loss puzzle. Other important factors that contribute to weight loss are diet and exercise. If you would like to lose weight and keep it off, here are a few tips:

  • Eat a well-balanced, nutrient-dense diet while avoiding high-calorie snacks in the evening.
  • Exercise regularly, which means at least 30 minutes of moderate-intensity aerobic exercise (brisk walking) 5 days a week combined with muscle strengthening exercise at least 2 times a week. (Check with your doctor before beginning an exercise program.)
  • Try to get at least 8 hours of sleep every night. 

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Julia Luksha is a dietetic intern at Brigham and Women's Hospital who received her Bachelor of Science in Nutritional Science at the University of Connecticut.


Jakubowicz D, Barnea M, Wainstein J, Froy O. "High caloric intake at breakfast vs. dinner differentially influences weight loss of overweight and obese women." Obesity. 2013.

Scheer FA, Morris CJ, Shea SA. "The intern circadian clock increases hunger and appetite in the evenging independent of food intake and other behaviors." Obesity. 2013.

Huang W, Ramsey KM, Marcheva B, Bass J. "Circadian rhythms, sleep, and metabolism." J Clin Invest. 2011;121(6):2133-2141.

Taheri S, Lin L, Austin D, Young T, Mignot E. "Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index." PLoS Med. 2004 December; 1(3):1-8.

Buxton OM, Cain SW, O'Connor SP, Porter JH, Duffy JF, Wang W, Czeisler CA, Shea SA. "Metabolic consequences in humans of prolonged sleep restriction combined with circadian disruption." Sci Transl Med. 2012 April 11; 4(129):1-19.

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