Why Am I So Hungry After Exercise?

woman feeling hungry after exercise looking in refrigeratorYou know the stereotype: People who exercise hard, then eat harder. I’m talking about the marathon runner-in-training lounging on the couch with a bag of chips beside them and a gallon of ice cream balanced on their chest, or the hardcore CrossFitter bankrupting the all-you-can-eat Brazilian steakhouse.

Perhaps you’ve even heard that you shouldn’t work out too much or too hard, lest you stimulate your appetite and end up negating all your fitness gains with your fork.

You might be surprised to learn, then, that the scientific evidence overwhelmingly suggests that exercise doesn’t make you hungrier. If anything, being sedentary is associated with dysregulated appetite and greater food reward.3 Exercise actually suppresses appetite, especially during and immediately after a workout.

Wait, So Exercise DOESN’T Make Me Hungrier?

I’m not saying that exercise never makes anyone hungry, nor that you’re imagining your post-workout yearning for a big, juicy burger. CAN exercise stimulate appetite? Absolutely. We’ve probably all experienced being ravenous after a heavy workout or a big race. But, it’s not inevitable.

You can probably also relate to finishing an intense workout or race and having no desire whatsoever to eat, sometimes for hours after. That’s because ghrelin—a.k.a., the hunger hormone—goes down after exercise, while satiety hormones like peptide YY rise. This well-known effect is called exercise-induced anorexia. (“Anorexia” here refers to a lack of desire to eat, not the eating disorder anorexia nervosa.)

That’s what happens in the short term. Over the longer term, studies suggest that the relationships between activity level and appetite and food intake follow a J-shaped curve. People who exercise moderately eat less and have less desire for food than folks who are either sedentary or very active.4 As activity level increases, so does food intake. It’s not that very active people are gorging themselves, though. They eat more, but their food intake is commensurate with their energy expenditure. In fact, highly active people often end up in a net caloric deficit despite eating more because of how many calories they burn.

All this points to the fact that exercise doesn’t inevitably cause uncontrolled appetite and overeating. That’s good news… unless you’re already experiencing unwanted hunger or cravings as you increase your activity level. What do you do then?

Why Am I So Hungry After Exercise?

You’re Not Eating Enough

Let’s start with the obvious. Hunger is your body’s way of telling you that you need fuel. Post-exercise hunger is often nothing more than a sign that you’ve created a caloric deficit that your body wants to attenuate.

The problem is many people who exercise also restrict their food intake. That’s ok to a degree, particularly if you’re trying to lose body fat. However, an alarming number of athletes and active folks drastically undereat relative to their caloric expenditure, leading to low energy availability. Sometimes this is unintentional. Other times, athletes purposefully maintain a significant caloric deficit to lose body fat and stay as light and lean as possible for their sports. Either way, it presents serious health risks. When it progresses to the condition known as Relative Energy Deficiency in Sport (RED-S), athletes may experience amenorrhea, osteoporosis, metabolic issues, cardiovascular disease, and more.

Researchers estimate that up to 58 percent of athletes maintain a state of low energy availability. That number might be low since there is no clear threshold for determining when someone crosses into the danger zone.5 Casual exercisers are at lower risk, but low energy availability is not restricted to elite athletes. Anyone who trains, especially with high volume or intensity, needs to take care to fuel appropriately.

Even if you’re trying to lose weight, it’s crucial to provide your body with the energy and nutrients it needs. Ravenous hunger and cravings are signs that you’re missing the mark. As you increase your activity level, make sure you’re adjusting your food intake to match.

 

Does Fasted Exercise Make You Hungrier?

It would make sense. You start your exercise without fuel in the tank, so you end up starving by the end, right? The limited data doesn’t bear that out, though. In the few studies that have tested it, both fasted and fed exercise lead to appetite suppression.6 The effect might be slightly stronger after fed exercise, but there’s no evidence that fasted exercise leads to excessive hunger, nor that fasted workouts drive you to eat more.7

One recent study suggests that fasting after exercise could increase hunger.8 Researchers had 14 participants complete 45 minutes of moderate-intensity cycling in the evening after dinner. In one session, participants had only water to drink after. In another, they received a sweetened milk beverage that delivered about 500 kcals. An hour later, the water-only participants reported being significantly hungrier.

Does that mean you should eat right after working out? Not necessarily. This was just one study, so your mileage may vary. Also, when participants in the study above woke up the next morning, they were no hungrier after the water-only condition. Nor did they eat significantly more at breakfast.

Still, if you’re getting very hungry after workouts, look at your post-workout fueling to see if you could tweak anything there. Perhaps you need to eat sooner or consume more protein in your next meal. Experts no longer believe that you have to consume protein right after a workout to hit your anabolic window, but you might find you feel better when you do.9  In any case, it’s not a good idea to put off eating until you’re consumed by a gnawing hunger. Eating W.H.E.N. (when hunger ensues naturally) should be fine, provided that you consume an adequate, nutrient-dense meal in a timely manner.

Maybe You’re Just Thirsty

That’s what any popular media article on post-exercise hunger would have you believe, anyway. The thing is, there’s not really any evidence that humans can’t tell the difference between being hungry and thirsty. They feel pretty different to me. I’m also not aware of any studies showing that drinking water during or after exercise attenuates hunger.

One hypothesis that holds more water (pun fully intended) is that you feel especially hungry after exercise because your body is seeking salt. Humans’ “sodium appetite” is well documented, and you lose sodium when you sweat.10 If you’re particularly drawn to salty foods after exercise, that’s why.

While I find the theory plausible, I can’t find any research linking sodium losses to post-exercise appetite. Make sure you’re hydrating and replenishing electrolytes after exercise anyway, but don’t necessarily expect that to curb your hunger.

Is It (Mostly) All In Your Head?

Ask yourself: Do you regularly treat yourself after hard workouts by indulging in foods that you normally don’t allow yourself to enjoy? Do you use exercise to “earn” your food? If so, what you’re perceiving as post-exercise hunger might actually be a learned association. It could be that you’ve trained yourself to expect “treats” after exercising. You’re not hungry so much as anticipating the forthcoming reward.

Learned associations are just habits, and they can be unlearned.

You Could Be Fatigued

Sleep deprivation leads to increased appetite, desire for highly palatable foods, and higher overall energy intake.11 12 Athletes and other highly active folks may need more sleep than average due to increased energy output during the day and greater need for recovery.13 Yet how many fitness-conscious folks get eight or more hours of sleep each night? Probably not many. More likely, they’re getting up at the crack of dawn to squeeze in a workout.

Becoming sleep deprived in the name of fitness is not a good tradeoff. For all the benefits of exercise, there are equally serious health risks associated with getting too little sleep. Out-of-control hunger could be a sign that you’re burning the candle at both ends and are headed for burnout.

Sometimes a Cigar is Just a Cigar… and Hunger is Just Hunger

All things considered, the most plausible explanation for post-exercise hunger and cravings is that you’re not eating enough to support your activity level. Your hunger is doing what it’s supposed to do—telling you to eat more. Insufficient sleep seems to be the next most likely culprit.

Thus, the first place to start is by ensuring that you’re eating enough—not just sufficient calories, but plenty of nutrient-dense foods that provide your body with the building blocks it needs. Figuring out how much to eat can be complicated, though, especially for people who are trying to shed body fat. In a perfect world, you’d let hunger be your guide, and that would be that. Studies do suggest that highly active folks seem to have more finely tuned satiety signals than their less active counterparts. This helps them regulate their food intake and refrain from eating more than their body needs in order to fulfill its energy requirements.14 On the other hand, fatigue, chronic stress, and our hyper-processed food environment can hijack hunger signals.

If you’re not ready to go with your gut, a calorie and macro calculator is an ok place to start. However, I wouldn’t recommend strictly eating according to what some algorithm spits out. It’s impossible to calculate your energy expenditure with any degree of accuracy, and you don’t want to ignore your hunger signals because an online calculator has decided you’ve eaten enough. Fighting your hunger and failing to nourish your body can lead to a dangerous restrict-binge cycle. Instead, the goal should be to use a combination of conscious analysis, planning, and intuition to experiment and find the diet-exercise combination that works best for your body.

Detach from the Emotionality of Hunger

At the heart of the question that drove this post—“Why am I so hungry after exercise?”—is the implicit assumption that it’s bad to be hungry after exercise, or any time. In today’s weight-loss and body-obsessed culture, hunger is feared and often reviled. It doesn’t have to be that way. Hunger is a neutral physiological signal. The meaning and emotions we layer over it are of our own making.

Try to observe your hunger without judgment. Ask yourself what your body needs and try to respond accordingly with food, sleep, comfort, or whatever else it’s asking for. Sometimes, accepting that it’s not only acceptable but often necessary to eat more when you increase your activity levels is easier said than done. Make sure you don’t use hunger as an excuse to avoid exercising.

Finally, remember that the opposite also isn’t true: exercise isn’t supposed to make you hungry, and hunger isn’t a sign that your exercise is “working.” Morever, exercise should never be a punishment for “bad” food choices, and you don’t need to be hungry as part of the atonement process. Move your body and fuel it appropriately so you can be healthy and strong well into old age.

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