HiiT training is changing the way people approach fitness training. That’s because even the most time-strapped person can fit exercise into their busy schedule with workouts as short as 20 minutes. HiiT training is an acronym for high-intensity interval training, a form of training that burns fat and increases both aerobic and anaerobic fitness.
By alternating periods of high-intensity exercise with periods of recovery, HiiT training lets you work out at a high intensity, an intensity you wouldn’t be able to sustain. Plus, high-intensity interval training is adaptable. By changing the exercises you do during the active intervals and the length of the intervals, you can use HiiT to meet a variety of training goals. No wonder it was one of the top ten fitness trends of 2014!
HiiT training burns a significant number of calories during the workout and during the recovery period when your body has to expend more energy to bring your body back to its resting state. The additional calories burned during the recovery period is called the “after-burn.” Not surprisingly, high-intensity workouts place more stress on your body than steady-state, moderate-intensity exercises. Your body temperature increases more, anabolic and stress hormones are produced, your heart and lungs have to work harder, fuel stores get spent and more lactate builds up in your bloodstream. During the recovery period, your body has to expend more energy to restore homeostasis. In general, HiiT training creates a more sustained after-burn so you continue to burn calories at a higher rate for hours after you complete the last interval.
With all of the additional energy expenditure during the recovery period, you might wonder what effect HiiT training has on appetite and whether you’re likely to compensate for the calories you burned during your workout by eating more. It makes sense that your body would respond to the calorie deficit created by a workout by making you hungrier. What does research say about HiiT training and appetite?
HiiT Training: Does It Make You Eat More by Increasing Your Appetite?
With regards to exercise in general, some studies show exercise reduces appetite for a short period of time after a session. In general, people feel less hungry during a workout and for an hour or two afterward. Does this lead to a decrease in calorie consumption? It depends on your gender. Immediately after a high-intensity workout, both men and women experience a reduction in appetite and don’t compensate for the calories burned during a sweat session by eating more — at least not right away. But when you look at calorie consumption over several days, women at least partially make up for calories burned through exercise by eating more. In contrast, studies show men don’t compensate for calories burned during a workout session by increasing calorie intake.
Why are women more likely to compensate for calories burned during exercise than men? No one knows for sure. It could be differences in appetite hormones or sex hormones like estrogen play a role or it may be more of a brain phenomenon. One study showed women feel more attracted to the sensory qualities of food after a workout. According to Dr. Timothy Fairchild of Murdoch University who studies the effect of exercise on hunger, people who are highly motivated to lose weight and are successfully doing it may be better able to ignore these hunger and sensory signals and maintain the energy deficit they incurred through exercise.
The Importance of Awareness
There’s another possible reason women eat more after a workout. It’s easy to get into the “I deserve it” mindset. When you’ve exercised hard, you can always rationalize why you should have that doughnut or chocolate chip cookie. Unfortunately, many people overestimate the number of calories they expended and end up negating any calorie deficit they accrued through exercise. It’s not hard to overeat a workout, even a high-intensity one.
The take-home message: Even if you do an intense workout, be aware of how much you’re eating. No one really likes the idea of counting calories but keeping a food journal for a few weeks will give you a more realistic idea of how much energy you’re actually taking in. You may be surprised to discover you’re eating more than you thought you were.
Avoiding the Problem of Overeating Your Workout
After a high-intensity workout, your body needs fuel for recovery. Make sure you’re feeding it “the good stuff” and not junk food. If you consume healthy carbs with protein after a workout, it’ll stabilize your blood sugar and reduce cravings for something sweet. When you don’t refuel in a healthy manner, your body is more likely to rebel and hit you with cravings for unhealthy foods. Make sure you’re eating small amounts of protein throughout the day to curb hunger after a workout.
Don’t forget to focus on hydration before, during and after a workout. Sometimes we confuse being thirsty with hunger. To make matters worse, dehydration and low blood sugar have similar symptoms — fatigue, lightheadedness and feeling weak. When you’re feeling hungry, drink a full glass of water and reevaluate how hungry you feel. You might discover your “hunger” has vanished.
The Bottom Line
High-intensity interval training has enormous benefits for health and body composition but you still have to be mindful of how much you’re eating, especially if you’re trying to lose weight. Keep a food journal to get a better handle of how much you’re taking in after a workout. Plan your after-workout snacks and make sure you’re eating protein regularly throughout the day. If you’re not losing the weight you expected, it may be because you’re compensating for calories burned by taking in more. It’s a common problem but one you can correct through greater awareness.
Am J Clin Nutr. Vol. 80. No. 5. S1230-1236. November 2004.
The American Council on Exercise. “The Truth about Exercise and Appetite”
Eur J Clin Nutr 1996;50. 663-667.
Women’s Health and Fitness Magazine. “The Exercise and Appetite Link”
Physiol Behav. Apr 26, 2010; 100(1): 22-32.
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