When should you eat most of your daily calories?

When should you eat most of your daily calories?

When it comes to arguments about nutrient timing, the trend in the fitness community over the last years was that it largely does not matter much as long as total daily calories and macro nutrients are in place.

But can we quantify „not much“ and what is so magic about about 24 hours? As a thought experiment, if nutrient timing really did not matter on a 24 hour basis, one could get all their nutrients in one huge meal each day. Now, many would argue that this is not optimal and you should spread your food intake more evenly over the day.

This study by Keim et al. (1997) had an amazingly controlled setup to investigate the effects of nutrient timing on body composition. They had 10 women in a metabolic ward* who underwent two different weight-loss protocols for 6 weeks.
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*A metabolic ward is a highly controlled environment where basically all of the participants’ lifestyle factors are controlled for (food intake, activity, etc.).
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In both protocols, the women did the same training protocol, consisting of strength training, cardio and walking. The difference lied in when the women consumed the bulk of their calories (either 70% in the morning or 70% in the evening)

Consuming most calories in the AM led to more weight loss than the PM – with a big caveat: it also led to more fat-free mass loss.

In fact, the body composition changes were better when consuming most calories in the PM. It led to MORE fat loss and LESS fat-free mass loss compared to the AM protocol – which is generally what you want to have from a diet!

The exact mechanisms for this was the case are hard to depict, but one can make the case for circadian effects of protein timing (the PM group had more protein later in the day) or generally better nutrient timing in relation to training.
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