Is Cardio Making You Eat More?by Liz Eberts, PT, DPT, OCS on December 3, 2015
Is Cardio Making You Eat More?
By Betsy Lane, CPT, SPT
“Eat less, exercise more!” We hear it all the time. It is the generic, all- encompassing prescription for weight loss that all of the magazines and trainers are harping. On the surface, it seems simple; but if it were, wouldn’t more of us be more successful? There wouldn’t be a need for diet and cardio plans, or weight loss coaches. Weight loss is complicated.
If we think about our metabolism as a balanced equation: when we exercise more (energy output), the body is naturally going to want to eat more, in the long run, to balance out (energy input). Seems kind of daunting, doesn’t it? Why exercise more, to burn more calories, only to make up for it with all of the food you end up eating when you’re starving? Don’t stop reading here, abandoning your cardio regimen. There is a solution. Read on!
The easy hack to reading this article is to read between the lines and shoot straight for the italicized summary statements in each section, and if you truly don’t care about the details and just want the cardio recommendations, shoot straight to the last section.
-Exercise suppresses your appetite during and after activity.
-Intensity and TYPE of the exercise makes a difference.
-In the long term, increased activity levels actually increase your overall appetite.
-What kind of cardio is best for weight loss?
1. First, understand some of the hormones involved
LEPTIN: Satiating hormone (The “stop eating” hormone)
Leptin is released from your fat tissues, in response to consuming carbs. When leptin is present, a variety of gut hormones (PYY and GLP- 1) are sent to your brain, to indicate that you are full; therefore, you won’t be so hungry, and your metabolism is heightened. When you are on a low carb diet, you might be starving, even despite consuming plenty of calories, because your carbs are low; therefore, your leptin will also be low, and your metabolism slows.
So in theory, if leptin is good because it eliminates hunger and results in a faster metabolism, then more carbs are better, right? Wrong. Actually, your leptin levels can also be too high for too long, which actually results in decreased satiety and slowed metabolism.
Like I said… it’s really not so simple as “eat less, exercise more;” there is a balance.
CARB CONCIOUS? SOLUTION: Don’t eliminate carbs entirely to ensure you keep your upper extremities in tact (should you be in the habit of biting them off in hunger), but obviously don’t binge on them. Try to focus them around your more active times during the day, such as pre and post workout, to really take advantage of your body’s energy systems.
GHRELIN: Hunger hormone (“I’m hungry!”)
When your ghrelin is high, YOU’RE HUNGRY! When leptin is high, Ghrelin is low. Ghrelin is the only gut hormone that lets your body know it is hungry, so of course, there is a lot of interest around this guy, in particular.
2. Cardio suppresses your appetite during the session and afterwards
Cardio actually suppresses your appetite. This happy phenomenon is partially attributable to a hormone called PYY, whose presence dictates strong appetite- suppressing effects. PYY and GLP-1 concentrations in your bloodstream are actually increased during and after bouts of high and moderate intensity cardio. Recall that these are both the hormones which alert your brain that you are full; essentially, cardio squashes hunger. (1,2)
One study found that elevated PYY responses lasted for as long as 5 hours after exercise, in comparison with the group that did not exercise. Several studies have noted decreased post- cardio food intake in their subjects, as well.
*HUNGRY OUT OF BOREDOM?
SOLUTION: GO SWEAT OFF YOUR APPETITE! HIGH AND MODERATE INTENSITY CARDIO WILL GIVE YOU NEWFOUND WILLPOWER AGAINST THE PIZZA.
3. Type of exercise and Intensity Matters!
Moderate and HIIT (high intensity interval training), and other bouts of high intensity exercise, such as sprinting or circuit training, temporarily suppress hunger, but resulted in increased food intake throughout the day, as indicated in several studies.
Researchers have found that those in a higher intensity, but SHORTER DURATION exercise group actually compensate with increased energy (food) intake less than those in the moderate intensity, longer duration (such as long distance running) groups.
Low intensity exercise, such as walking, seemed to have no effect on satiety OR increased energy intake.
IN SUMMARY: moderate and high intensity cardio suppress your appetite after and during exercise, but both eventually result in increased food intake compensations. BUT, the higher intensity and shorter duration of your workouts, the less you will compensate by eating more later!
That’s’ good news for all of us, because studies have shown time and time again that HIIT exercise is the most effective kind of cardio for fat loss. AKA you’re on the dreadmill for less time, and you’re more effective, and less hungry than you would be with an hour of mod intensity cardio ?
*WALKING AWAY YOUR WHOPPER WOES?
SOLUTION: SPEED IT UP AND CUT THE TIME IN HALF; HIIT IS YOUR NEW HAMBURGER HATER.
What about weight training? Studies have found that [the awesome satiety hormone,] PYY concentrations in the bloodstream were not affected. BUMMER! I would venture to speculate that if you were engaging in intense circuit training/ HIIT style weight training activities that resembled the heart- pounding intensity of a moderate intensity run/ jog, you would still be effectively raising your PYY.
4. In the long term, cardio will make you eat more, however, doing less cardio doesn’t technically make you eat less
One study found that women who participated in a week- long cardio (medium and high intensity) program compensated for the “calories burned” by eating more calories than they would have otherwise. However, they only compensated by eating 33% of the “calories burned.” On the other hand, all of the women in the cardio study lost small amounts of body fat. Energy and calorie intake did not change in the group that did not exercise; they actually gained body fat.
IN SUMMARY: Simply adding in some cardio alone might help you to lose SOME body fat; but AVOIDING it will cause you to GAIN body fat.
*In short: There is no evidence that exercise will make you eat the equivalent (or more) of all of the calories you just burned, therefore making exercise totally obsolete.
SOLUTION: BE AWARE OF THE ENERGY IMBALANCE AND DO CARDIO FOR FAT LOSS. YOU AREN’T GOING TO OVERCOMPENSATE BY EATING SO MUCH THAT IT DESTROYS YOUR EFFORTS, ACCORDING TO THE RESEARCH.
5. What kind of cardio should I do? WELL.. Several options with varying benefits
Low intensity cardio: Choose this if you are all about burning up extra calories, but HIIT makes you absolutely starve your brains out all day. I personally cannot do “fasted cardio,” unless it is low intensity, because I won’t be able to stop thinking about food until I eat everything in my cabinets, and enter the food coma zone. Talk about energy compensation! A low intensity walking program might be for you. Note that while this article advocates for a moderate to high intensity version of cardio for optimal benefits of fat loss, it does not intend to make a case AGAINST other forms of cardio. A walking program, especially in the beginning of your fitness journey, can be enormously beneficial for all of your body systems as a whole (what’s good for the heart is good for the brain, too). Low intensity has other benefits as well, when we talk about preserving muscle in an extreme caloric deficit. Bodybuilders have been advocating for low intensity walking programs during their dieting season for years.
THE BEST KIND OF CARDIO IS THE KIND THAT YOU WILL STICK TO CONSISTENTLY.
Short bouts of moderate to high intensity cardio: for the quicker, and more efficient way to stimulate body fat loss, compared to low intensity walking programs. Be aware that this will still cause increased appetite, but NOT ENOUGH to compensate for all of your hard work (according to the studies).
Short bouts of high intensity exercise for appetite- suppressing effects- shortly after dinner, for example, if your problem is night time eating due to boredom/ exhaustion, etc. I have used this method during contest prep; I would always save my cardio for evening time, after meal 5 (that means I still had one meal left, to kick off the night… booooooo yeaaaahhhh, protein pancakes!).
I personally propose: a mixture of the two, even during a caloric deficit. A walking program is great for general health, and will improve your blood work across the charts, and can result in weight loss, if you are currently sedentary. Walking is good for everyone; 10,000 steps/ day is recommended for general health purposes, and less than 5,000 steps is considered sedentary.
***Sitting for 6+ hours/ day increases the chances of all- cause mortality by more than 10 fold. Walking is NEVER a bad idea, especially if you have a sedentary job.
Then, on the other hand, HIIT is great for fat loss. I don’t even need to cite that, because you can just pop that one into Dr. Google and you’ll get a million hits.
IN SUMMARY: I’m suggesting HIIT for fat loss, and then low intensity for increased calorie expenditure, without an additional appetite stimulating effect, (*though I haven’t found any literature to support that combination specifically). I am my own personal guinea pig for this method, especially during contest prep, when my energy intake is low, and also because I have difficulty with avoiding night time eating habits. One example of such a cardio session might include 10- 15 min. HIIT via treadmill sprint intervals (after stretching thoroughly, especially calves), followed by 10- 20 minutes of treadmill walking.
*SOLUTION: Keep in mind that the best cardio for health/ weight loss/ whatever your goals are, is the kind that you will ENJOY the most, because it is the one that you will be most likely to CONTINUE.
1. Stensel D. Annex of Nutrition and Metabolism. 2010;57:2. 36–42
2. Martins et al. Effects of exercise on gut peptides, energy intake and appetite. Journal of Endocrinology. 2007;193. 251-258
3. M Pomerlau et al. Effects of exercise intensity on food intake and appetite in women.
American Journal of Clinical Nutrition. 2004;5. 1230- 1236