Chocolate First Thing in Morning May Reduce Waist Size Interview with:
Frank A. J. L. Scheer, PhD, MSc,
Neuroscientist and
Marta Garaulet, PhD, Visiting Scientist
Division of Sleep and Circadian Disorders
Departments of Medicine and Neurology,
Brigham and Women’s Hospital. What is the background for this study?

Response: We and others have shown that not only “what” but also “when” we eat relates to obesity and weight loss

  • Meal timing can influence circadian rhythms and eating a high energy and high sugar food, such as chocolate, either at night or in the morning may have a different effect on the circadian system, and consequently on body weight and metabolism.
  • Milk chocolate has a name for contributing to weight gain due to its high fat, sugar and caloric content. Chocolate eating habit has been associated with long-term weight gain especially in postmenopausal females who are particularly vulnerable to weight gain. What are the main findings? 

chocolateResponse:  Surprisingly a big amount of chocolate (100g) consumed in a narrow window of time (1h just after getting up) and (1h before going to bed) did not result in an increase in body weight in the postmenopausal women studied . Of interest, females reduced waist circumference when having chocolate in the morning

This randomized controlled trial study suggests that chocolate, in the morning or in the evening/night, in a narrow window of time (1 h), results in differential effects on hunger and appetite, substrate oxidation, fasting glucose, microbiota composition, and sleep.

The intake of a rather high amount of chocolate (100 g) concentrated in a narrow (1 h) timing window in the morning could help to burn body fat and to decrease fasting glucose levels in postmenopausal women. What times of day were best for chocolate intake? 

Response: It depends on the effect which we are looking for.

Chocolate in the morning may have effects in helping to burn body fat, decreasing glucose levels or waist circumference, while Evening/night chocolate may induce carbohydrate oxidation as previously seen in studies where pre-sleep chocolate milk changed next-morning resting and exercise metabolism to favor carbohydrate oxidation. Therefore, chocolate intake at evening/ night might be considered for next morning performance during high intensity exercises or prolonged exercises and thus avoid hepatic and muscle glycogen depletion. Does hot a cup of hot chocolate with breakfast suffice?

Response: A cup of hot chocolate has approximately 200 calories (less than half of the calories used in the current study). We wanted to perform this study in extreme conditions for research, but a cup of chocolate for breakfast, during the 1hour after getting up, without having any chocolate the rest of the day, may have similar effects, although presumably less strong. What should readers take away from your report?

Response: If they want to eat chocolate, in order to prevent body weight gain, it could be considered to consume it in a narrow window of time, during the 1h just when getting up in the morning, without eating more chocolate in the rest of the day.

For those who usually do exercise in the morning (high intensity exercises or prolonged exercises) it could be considered to consume chocolate during the previous night, in a narrow window of time of 1 hour just before going to bed. What recommendations do you have for future research as a result of this work?

Response: It is relevant to study whether these results are similar for men or younger women, or to extend the study for longer periods (longer than two weeks) to see if the effect on body weight or the metabolic effects are similar. It is also relevant to know if the effects are due to the energy content of chocolate or to the macronutrient compositions or to other components of chocolate such as methylxanthine such as caffeine or theobromine or other chocolate compounds such as polyphenols. Is there anything else you would like to add? 

Response: We have to be cautious. This is the first study to analyze the intake of milk chocolate in different timings of the day. Future studies are needed to test whether these effects last beyond two weeks and to test these effects in other populations, including in men, different age groups and other vulnerable populations, such as patient with obesity and diabetes.


Hernández-González, T, González-Barrio, R, Escobar, C, et al. Timing of chocolate intake affects hunger, substrate oxidation, and microbiota: A randomized controlled trial. The FASEB Journal. 2021; 35:e21649.



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Last Updated on June 24, 2021 by Marie Benz MD FAAD