While maintaining good habits during the day—eating well, exercising regularly—are crucial for weight loss, resting at night is just as important for keeping off the pounds. In a study published by Plos One journal last year, researchers found that people who skimped on sleep were more likely to have higher body mass indexes and larger waist circumferences than those who got adequate shut-eye.
Another misconception about HIIT is that it will cause muscle loss. This is just not true either. This myth got started because a higher amount of calories burned during HIIT will come from stored amino acids (muscle tissue) when compared to lower intensity cardio. As long as HIIT sessions are kept to a short duration muscle loss not be a problem. In fact, muscle growth and muscle retention are increased due to the effects HIIT has on anabolic hormones. Just one 10-15 minute session of HIIT can increase testosterone and growth hormone levels for hours after the workout has ended.
When you start reducing your calories to create a healthy calorie deficit, you may start to feel hungry as you adjust to your new calorie intake. You don't want to ignore physical cues of hunger such as dizziness, headaches, the inability to concentrate, and extreme fatigue, but one of the reasons people struggle to lose weight is because they don't eat satiating meals and instead allow themselves to feel hungry all day. This isn't sustainable and such restriction often ends in binge-eating or giving up.
This may explain why the fat-burning effects of eating more protein were confirmed in a study published in the American Journal of Physiology. One group was fed a high-protein diet (just over 1 gram per pound of body weight per day) while the second group consumed an amount closer to the lower recommendation of the RDA (recommended dietary allowance). The group eating the higher-protein diet burned the most fat.