People often think that low-intensity exercise, in which your body taps into fat metabolism, is the most efficient way to lose body fat. Some cardio machine displays even claim that you’re in the fat-burning zone when your heart rate is low and that you exit the zone once your heart rate rises. Physiologically, the second part of that statement isn't true.
When you eat carby, sugary foods and snacks, you end up with the all-too-familiar sugar spikes and energy crashes. That’s all due to insulin, which skyrockets when you eat carbs. Insulin also tells the body to store calories as fat — and most people trying to lose weight aren’t looking for extra padding in the belly or thighs. Since dietary fat has less impact on insulin levels than carbohydrates or even protein does, you don’t have to worry about sugar crashes, cravings or storing rolls of body fat.
All animal proteins are also a good source of tryptophan, which is a precursor to the neurotransmitter serotonin. “If you struggle with mood or stress, it’s important to boost the production of serotonin to stabilize your mood, curb emotional eating, and keep stress-induced snacking at bay," especially when you’re trying to lose weight, says Cording. But when it comes to portions, opt for a 100 gram serving, which is about the size of a deck of cards, for reference.
Nighttime snacking may be even worse than we thought. When researchers fed rats the same number and kind of calories but varied whether they ate them over an eight- to ten-hour period or a 15- to 24-hour span, the late night diners became obese while the rats who noshed only during the day lost weight. While they haven’t identified exactly why this occurred, they believe it has something to do with eating in line with circadian rhythms, or our bodies’ natural internal clocks, which can be triggered by environmental conditions such as sunlight. When researchers repeated the study with humans they got similar results—seems like a good idea to quit eating at sundown.