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Chronobiology: Are all Calories Created Equal?

Updated: Feb 22

In this video I read an excerpt from Dr. Greger's book titled 'How Not to Diet.' More specifically, I read about the most optimal times to eat.

Main Points:

  • Study subjects ate the same number of calories over a twelve week period; however, one group had their caloric distribution as 700 calories at breakfast, 500 at lunch, and 200 at dinner; the other group had the inverse: 200 calories at breakfast, 500 for lunch, and 700 at dinner.

  • The group who consumed the 700 calories at breakfast lost 19 pounds over 12 weeks, while the group who consumed 200 calories at breakfast lost 8 pounds over the same period.

  • Conclusion: When you consume calories seems to matter significantly. Eating the majority of your calories at the beginning of your day is conducive to losing weight.

Excerpt from page 319 of How Not to Diet (as read in video above):

Skipping breakfast has been described as a "straightforward and feasible strategy" to reduce daily calorie consumption.

Unfortunately, skipping breakfast does not seem to work.

Most randomized controlled studies of skipping breakfast on no weight-loss benefit. How is that possible if skipping breakfast means skipping calories? The bath breakfast project, a famous series of experiments run not out of a tub but at the University of Bath discovered a key to this mystery. Men and women were randomized either to fast until noon every day or to eat breakfast, which was defined as taking in at least 700 calories before 11:00am. As in other similar trials, the group eating breakfast ate a little less throughout the rest of the day, but still ended up with hundreds of excess daily calories over those who had skipped breakfast. Yet after six weeks, both groups ended up with the exact same change in body fat. How could hundreds of calories a day just effectively disappear?

Recent breakthroughs in the field of chronobiology -- the study of our body's natural rhythms -- have appended another key piece of nutrition dogma: the concept that a calorie is a calorie. As it turns out, it's not just what we eat but when we eat. Because of our circadian rhythms -- circadian coming from the Latin words for about and day -- morning calories don't appear to count as much as evening calories.

[Pg. 323-4]:

What about just shifting our daily distribution of calories to earlier in the day? Israeli researchers randomized overweight and obese women into one of two isocaloric groups, meaning each group was given the same number of total calories. One group was given a 700 calorie breakfast, a 500 calorie lunch and a 200 calorie dinner and the other group was given the opposite -- 200 calories for breakfast 500 for lunch and 700 for dinner. Since they were all eating the same number of calories overall, the king-prince-pauper group should have lost the same amount of weight as a pauper-prince-king group, right? But no; the group who ate the most at breakfast lost more than twice as much weight as the group eating the most at the dinner meal.

In addition to slimming nearly an extra two inches off their waistlines, by the end of the twelve-week study, the king-prince-pauper group lost 19 pounds compared to only eight lost by the pauper-prince-king group despite eating the same number of calories. Eleven additional pounds loss eating the same number of calories. That's the power of chronobiology.

End of excerpt.

(I have to include a picture somewhere on this page otherwise a thumbnail image won't appear)

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