Q&A: Eating milk chocolate in the morning stimulates fat metabolism
reark chocolate is often boasted as a heart-healthy and relatively nutritious snack, but most chocolate candies are made from milk chocolate, a version that is higher in fat, sugar and calories. Recent studies found that giving rats milk chocolate when they wake up prevents their circadian rhythm from being disrupted during simulated jet lag, adding to a long line of proof showing that when what we eat can affect our health as much as what goes on in our stomachs.
To better understand how the timing of milk chocolate consumption affects human health, the authors of a new study, published June 24 in The FASEB Journal, 19 postmenopausal women each underwent a series of two-week experimental sessions in random order, with one-week breaks in between. The sessions included one session in which they did not eat chocolate, another where they ate 100 grams of milk chocolate within an hour of waking up, and one in which they ate the same amount of chocolate but an hour before waking up. go to bed. During each two-week phase, the researchers tracked metrics such as the women’s weight, hunger and cortisol levels, the number of calories they consumed each day in addition to chocolate, physical activity, oxidation of lipids and carbohydrates (a measure of energy expenditure), glucose metabolism and changes in their gut microbiota. One of the conclusions of the study was that neither of the groups gained weight and that, in fact, eating chocolate in the morning resulted in a decrease in women’s waistlines and fasting blood sugar, potentially reducing their risk of prediabetes and other metabolic disorders.
The scientist spoke with two authors of the article – Frank Scheer, neuroscientist and professor of medicine at Harvard Medical School, and Marta Garaulet Aza, nutritionist at the University of Murcia in Spain and visiting scientist at Brigham and Women’s Hospital – on how the timing of eating chocolate could affect our bodies in different ways.
The scientist: What was the impetus of this study?
Marta Garaulet Aza: There was an abstract presented by Carolina Escobar, who is also the author of our article, at a meeting on sleep several years ago. And she demonstrated that the timing of chocolate consumption can impact the circadian system [in rats]. Because we have been working for many years on when to take food, we thought we could make a very popular food. In my clinics everyone loves [chocolate], and we never know what to do with our patients. If we forbid it, they look for it, they want it [it] After. . . . We wanted to see what happens with this great amount of energy, a special food that everyone loves and is known to make you gain weight. So we looked at two times of the day to say, “How does that impact metabolism differently?” ”
Frank Scheer: This builds on previous work we had done, as well as other labs, where we investigated the role of timing of nutrient intake on metabolism. Animal experimental work, as by Carolina Escobar, shows that if you don’t take the time to eat, it can lead to obesity and problems with blood sugar control, as well as in the lab studies we’ve done in humans showing that the Schedule eating the same meal makes a big difference in blood sugar control, as well as energy expenditure. Food-induced thermogenesis, for example, is the increase in energy expenditure after eating a meal. And we can see that if you do this in the morning or in the evening that you have very different answers, which may help explain the associations that have been found between timing of feeding and risk of obesity, or timing of feeding and other metabolic problems.
ST: I think we often hear about the health benefits of dark chocolate, but you used milk chocolate here. How did you come to this decision?
Marta Garaulet Aza
MGA: We made this decision because [Escobar’s] study in mice was done with this type of chocolate. And also because it is the most popular chocolate, at least in Spain. And the second thing is because we know that dark chocolate is very well accepted in society because of the polyphenols, epicatechin, catechins, theobromine and caffeine, and the effects on weight loss. But we wanted to opt for a not so extreme chocolate, not so well accepted, to see if it had too [the same properties associated with dark chocolate].
ST: The women in the study ate 100 grams of chocolate at each session. It sounds like a lot of chocolate! It’s almost an entire bar, or an entire bar, depending on the brand. Why did you land on this number?
MGA: In Spain there is a very popular brand called Nestlé. And that’s the size everyone has at home. . . so we used the most common. . . . And we wanted that to be 30% of the total daily calories in this type of population because it was the same as Carolina Escobar did. [in mice].
It was another reason to use milk [chocolate]. Some women couldn’t eat that much dark chocolate.
ST: What can we learn from this study? Is there any good news for those of us who love to eat chocolate?
FS: One of the surprises was that despite eating nearly 550 kilocalories [of chocolate] per day for two weeks, people did not gain weight, either in the morning or in the evening. And people were their own control because it was a balanced randomized crossover design, so the study is quite sensitive to detecting changes within the person. We would have expected to find changes if they were significant.
It becomes interesting in that morning and evening differ a bit. Therefore [when women consume chocolate] in the morning, it appears that they compensate more by reducing the other food intake of the day. . . more than the evening group. But the evening group showed an increase in physical activity. So it was kind of a difference. The other was that the morning group had more fat oxidation, as opposed to the evening group, which had more carbohydrate oxidation. The mechanisms therefore appear to be different, but both did not lead to any weight gain in these two cohorts.
I think the other, more clinically relevant observation was that fasting blood sugar decreased in the morning group as well as waist circumference. And the waistline is pretty amazing when you think about the amount of calories chocolate consumes. It is really believed that waistline is primarily related to visceral fat, which has been linked to unwanted metabolic effects. Now it’s a two week exhibition course. Tracking would be what happens if you do this on a more chronic basis.
MGA: Chocolate in the evening can be good if people have to do high-intensity exercise the next morning, but for the general population who don’t want to gain weight, maybe they want to have chocolate in the morning.
ST: I know you watched a bit how the microbiota changed after eating chocolate. I thought it was a particularly interesting find. Can you tell me a little more about this?
FS: There have been a lot of changes related to the microbiota, as well as metrics that reflect the metabolism of the microbiota. For example, [in both groups that ate chocolate] there has been a decrease in Firmicutes, which in the past have been associated, although there is still much debate on this issue, with the risk of obesity. And then with regard to measurements of microbiota metabolism, such as short-chain fatty acids, these have also been associated with beneficial metabolic phenotypes. So I think this type of work, like good science does, raises more questions than it answers. But yes, a rather striking effect and also interesting to see that, once again, there are some differences according to the times.
MGA: When we did an analysis of the main components, the bacteria and also the metabolites, therefore the short chain fatty acids, we find that they have a different profile in the morning, in the evening, and in the control. [groups]. That, for me, is very nice. The other thing is that the morning chocolate, even if both [times] had the same effect, the same direction, was more effective in changing the microbiota than evening chocolate.
ST: You mentioned in the document that the mechanisms behind some of these things will require further study. But given that you’ve seen different results between day and night, do you have any working assumptions about what you think is going on here?
FS: I think the question on the mechanism is always difficult. Of [the point of view of] weight control, a number of physiological and behavioral changes occur, such as reducing other foods. But we can think about it. Is it the energy content of chocolate? Is it the hedonic aspect of chocolate, that it makes people happy, that it helps them reduce other calories more easily? Are these results due to the effects of energy timing on metabolism? If you eat chocolate in the morning, for example, does the body perceive this kind of excess energy to increase energy expenditure or decrease cravings? And then, in addition to the hedonic mechanisms and energy balance mechanisms, could it be something more specific to the micronutrient content of chocolate?
To find out which of these would require repeating a study like this where you exclude theobromine or other things. [in chocolate] and see if you get the same kind of effect. And of course, in humans, these tests are very long, very expensive, very laborious. We could then consider testing some of these ideas first in animal experiments and then replicating them in human trials to be more effective.
ST: Is there any reason to believe that the results you found would be different for premenopausal women?
MGA: We don’t know, but why not? If the mechanism is related to energy. . . it is not a specific thing for the postmenopausal woman. If it was related to the decrease in certain hormones related to menopause, maybe it was, but we didn’t find that.