woman eating late night snacks watching tv

Is Late-Night Snacking Undermining Your Efforts to Burn Fat?

By the wlr team

Key Takeaway

  • If you tend to snack later in the in the evening, you could be making it harder for your body to burn fat stores

The balance between weight gain and weight gain loss is predominantly determined by what you eat, how much you eat, and by how much exercise you get.

But another important factor is often neglected...

Research from Vanderbilt University, shows that it's not just how many calories you eat, but when you eat them that could determine how well you burn off fat.

Your daily biological clock and sleep regulate how the food you eat is metabolized; thus the choice of burning fats or carbohydrates changes depending on the time of day or night.

Your body's circadian rhythm has programmed your body to burn fat when you sleep, so when you skip breakfast and then snack at night you delay burning the fat.

The Study

Researchers monitored the metabolism of middle-aged and older subjects in a whole-room respiratory chamber over two separate 56-hour sessions, using a "random crossover" experimental design.

In each session, lunch and dinner were presented at the same times (12:30 and 17:45, respectively), but the timing of the third meal differed between the two halves of the study.

Thus in one of the 56-hour bouts, the additional daily meal was presented as breakfast (8:00) whereas in the other session, a nutritionally equivalent meal was presented to the same subjects as a late-evening snack (22:00).

The duration of the overnight fast was the same for both sessions.

The Results

  • The two sessions did not differ in the amount or type of food eaten or in the subjects' activity levels
  • The daily timing of nutrient availability, coupled with clock/sleep control of metabolism, flipped a switch in the subjects' fat/carbohydrate preference such that the late-evening snack session resulted in less fat burned when compared to the breakfast session

The timing of meals during the day/night cycle therefore affects the extent to which ingested food is used versus stored.

Researchers Say:

This study has important implications for eating habits, suggesting that a daily fast between the evening meal and breakfast will optimize weight management.

WLR Tips to Beat the Evening Munchies

  • Try eating breakfast if you don't already to see if that reduces the urge to snack later in the day
  • Make sure dinner is sunbstantial with plenty protein and fibre, both of which help to fill you up
  • If you always fancy something sweet in the evenings, have some grapes, strawberries or other sweet fruit shortly after dinner
  • Make yourself a rule that you won't eat after a certain time in the evening, brush your teeth at that time to encourage yourself to comply
  • Take the things you usually snack on the evenings off your shopping list 


Kelly KP, McGuinness OP, Buchowski M, Hughey JJ, Chen H, Powers J, et al. (2020) Eating breakfast and avoiding late-evening snacking sustains lipid oxidation. PLoS Biol 18(2): e3000622. https://doi.org/10.1371/journal.pbio.3000622

Useful Links


For people with an eating disorder, BEAT recognises the problems of night time binge eating.

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