Hello!

If you've been around diet blogs for a while, you've probably come across at least one person suggesting an "inverted" meal plan, wherein the most caloric meal of the day is breakfast and the least caloric is dinner, in opposition to most people's meal planning.

For example...

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Supporters of this method have claimed that this inverted calorie amount helps with weight loss and glycemic control by matching up your daily intake with your body's natural circadian rhythm. This article will cover the results of a few papers testing this theory. The papers will be cited with numbers corresponding to a pubmed, pmc, or doi code.

The Data

According to Ravussin et al., 2019, eating from 8am to 2pm (time-restricted feeding, eTRF) is associated with more weight loss than eating normally from 8am to 8pm, but the difference is largely from reduced appetite, not increased energy expenditure (thermogenesis) (1). This study was "isocaloric" during the measurement of energy expenditure and substrate oxidation in a chamber over 24 hrs, meaning both groups' participants had to eat the same amount of calories during this observation period, and the scientists measured whether or not their bodies "burned" more calories over 24 hours in the eTRF group versus the normal group. They did not.

However, on the other side of the argument, we have Jakubowicz et al, 2021, which is a review article which has claimed that there may be altered thermogenesis if breakfast is skipped, contributing to weight gain in clinical, non-diabetic and non-obese studies; however, I went through the citations for this claim, and none of them provide this evidence for altered thermogenesis. Pre-clinical studies and studies involving obese and diabetic patients, however, may display this evidence, which is where the claim could have come from (2).

This same author in 2013 performed a study with obese patients split into two groups: the breakfast group (700 kcal) (BF) and the dinner group (200 kcal breakfast, 700 kcal dinner) (D). Note that these groups were theoretically fed the same amount of calories per day; however, it was up to the discretion of the patient to log their calories. They also do not record or make sure exercise is the same between the groups. The BF group showed greater weight loss and waist circumference reduction. Although fasting glucose, insulin, and ghrelin were reduced in both groups, fasting glucose, insulin, and HOMA-IR decreased significantly to a greater extent in the BF group. Mean triglyceride levels decreased by 33.6% in the BF group, but increased by 14.6% in the D group. Oral glucose tolerance test led to a greater decrease of glucose and insulin in the BF group. In response to meal challenges, the overall daily glucose, insulin, ghrelin, and mean hunger scores were significantly lower, whereas mean satiety scores were significantly higher in the BF group (3).

So, which one is it? Does the 700 kcal breakfast alter thermogenesis or only your appetite? Its Jakubowicz et al., 2013 versus Ravussin et al., 2019. Though the former lasted much longer than the latter (among other differences in methods), thermogenesis/energy expenditure needn't a long period of time to be recorded, only 24 hours. Both found that fullness, and maybe fat oxidation, increase when most calories are consumed earlier in the day, as opposed to later, around people's usual dinner time. The fatal flaws in Jakubowicz' experiment are these: (1) the patients' accounts may be inaccurate, since they are policing the calorie limits themselves, and (2) Jakubowicz is assuming thermogenesis must be increased (instead of the hungrier group simply eating more and fudging their calorie diaries), but 24 hr energy expenditure is never directly measured, as it is in Ravussin et al., 2019 under direct observation by the scientists.

Conclusion

There you have it. It is unlikely that time-restricted eating contributes to weight loss because of thermogenesis, but it does contribute to weight loss by making you feel fuller.

In other words, if you're counting calories and are good and honest with it, do whatever is more convenient for you. Eating 1400 kcal normally is not any different from eating 1400 kcal with this inverted, big breakfast method, except with respect to your feeling of "fullness" during the day. Personally, since my dinners are not malleable (I eat with a non-dieting person in the evenings; plus, I want the freedom to get take-out, which we do maybe once per week, without feeling super stressed about overshooting my daily calorie "allowance" that's already at 1200 / 1400 kcal with this method!), sometimes skipping breakfast and having a light lunch ( 200-400 kcal ) and maybe a late afternoon snack ( > 100 kcal ) is easiest for me to maintain a proper kcal limit, day to day.

References

(1)
PMID: 31339000

(2)
PMID: 34063109

(3)
https://doi.org/10.1002/oby.20460