The problem is that theory is wrong. Research published by scientists does indicate that energy expenditure decreases by about 35% during the first half of a sleep cycle[1]. The problem is that the same studies show that during the second half of a cycle—the REM phase of sleep—energy expenditure increases dramatically. What essentially happens is a rise and fall of metabolic rate during sleep.
Overall, energy use ends up leveling itself out. A study published in the European Journal of Clinical Nutrition demonstrates that while metabolic rate does drop at certain points during sleep, overnight energy expenditure is not much different from daytime energy use[2].
What About Time of Day?
Many nutrition gurus who say that you shouldn’t eat carbs at night talk about insulin response. They say that insulin levels remain elevated longer after evening meals. That, according to research, is correct. The reason, however, is simply because people don’t eat while sleeping. You have to remember that the first meal of the day occurs after a long fast—of course there will be a dramatic response from your body.
One study, published in The American Journal of Physiology, determined that “time of day did not significantly influence maximum postmeal increment in insulin secretion rate or duration of insulin secretary response.”[3] In common terms, that means that it doesn’t matter when you eat—insulin response will be the same.
So What’s the Deal?
The conclusion is that the “no carbs at night” idea is a complete myth. Scientific research does not back the idea that you can’t eat carbs at night if you want to lose weight. Studies prove that your metabolic rate does not significantly change, or does not change enough to have an impact when it comes to weight loss.
So, what can you do? Here is a tip—a recent study shows that people who don’t exercise have a lower metabolic rate while sleeping than people who frequently work out[4]. That makes sense, because people who are sedentary generally have lower base metabolic rates. Their bodies don’t use as much energy as active people.
If you want to lose weight, stop worrying about meal timing and just get some exercise. Spend all the time you currently spend worrying about when to eat and how to do it and work out instead. That type of dedication is the key to weight loss success.