Does Exercise Make You Hungry or Suppress Your Appetite?
Sometimes, when Jessica Crandall finishes a run, she's nearly disgusted by the thought of eating. "Even if I get the smell of food, it makes me feel like, 'ugh,'" says Crandall, a registered dietitian in Denver who works with athletes. Other times, when she wraps up a high-intensity interval training workout, her stomach growls. And, after yoga, she often feels full – spiritually, sure, but also physically. "Yoga actually decreases my hunger," she says.
Is there a rhyme or reason to how different exercises affect Crandall's hunger?
"There are many factors that can play into level
of physical activity and impact on appetite," including body fat
percentage, fitness level and ability to recognize hunger cues, says Melinda Manore, a professor in the department of nutrition and exercise sciences at Oregon State University.
Most research
shows, for example, that exercise decreases levels of the
appetite-stimulating hormone ghrelin and increases levels of the
appetite-suppressing hormone leptin. But other research
suggests that exercise's apparent hunger-suppressing effect doesn't
apply to obese women the same way it does to lean women. Other variables
like the temperature outside or in the studio, a city's altitude and, for women, where they are in their menstrual cycle matter too.
Here's a closer look at some of the many factors
at play – and how to use them to your advantage to achieve your health
and fitness goals:
1. Intensity
While an intense spin class burns more calories
than a leisurely walk, harder workouts tend to temporarily suppress
appetite, while low- to moderate-intensity exercise can make you feel
hungry quickly. That's because, during a challenging routine, your body
shuttles much of its blood supply to the heart, brain and muscles. Your
digestive system, meanwhile, gets more or less abandoned. "The harder
you exercise, the more blood you're pulling away from the gut and the
less hungry you're going to feel," explains Lara Dugas, an exercise physiologist and researcher at Loyola University Chicago.
Once you've recovered from a challenging workout, though, cravings will kick in. "If you have nothing in your gut, you're going to be starving," Dugas says. To prevent overeating,
plan your post-workout meal or snack before working up a sweat,
Crandall suggests. "Plan your meals [to be] more nutrient-rich or high
in fiber, so you fill up on nutrient-rich foods versus high-calorie
foods."
2. Duration
The longer you exercise, the longer it's going
to take for your body systems to return to baseline and cue your hunger.
So, after a two-hour run, you may be able to shower, get dressed and
drive to a restaurant before the menu looks appealing, while after a
20-minute high-intensity interval training session, you may not make it
home from the gym without stopping for a snack. Longer exercise also suppresses your appetite in the way that it fills time you may otherwise spend mindlessly eating, says Keri Anderson, a nutrition coach and personal trainer at Life Time Plymouth in Minnesota.
If you are a distance runner or other long-duration exerciser,
don't wait until you're starving to refuel since getting in nutrients
30 to 40 minutes after exercise can aid recovery. Instead, drink
something easily digestible like a shake or smoothie relatively soon
after exercising and eat a moderate, balanced meal when hunger – but not
starvation – kicks in.
3. Novelty
Whether she's trading weightlifting
for cardio or training with kettlebells for the first time, Mercedes
Elsen can feel the effects of a new fitness regimen in her stomach. "I
wake up famished," says Elsen, a 27-year-old hair stylist in Minneapolis
who trains with Anderson. Indeed, any activity that challenges you in a
new way can affect your metabolism, caloric output and hunger level
throughout the day.
"Some people, when they enter a strength phase,
they'll [say], 'I don't know what's going on, I just can't control my
appetite," Anderson says, while other people like Elsen feel most
ravenous when doing cardio. Tracking energy output and input with an app like My Fitness Pal can help prevent you from overestimating how much you burned – and overcompensating at your next meal.
4. Your Diet
Many people find that endurance exercise
stimulates hunger more than strength-based programs, but how they're
fueled – with carbohydrates versus protein – could also be at play,
Anderson says. "If you're a cyclist or runner, it's more carb-rich
diets; they're eating things that for some folks could stimulate hunger,
whereas more bodybuilders typically hang around the crowd that eats
meat and protein," she says. "Is it that they're satisfied because of
weightlifting or is it because they're so protein-focused?" She
recommends a diet rich in protein and fiber for most athletes, but
working with a fitness professional with expertise in nutrition can help you craft a diet that supports your training and goals.
5. Your Mentality
Understanding how exercise affects hunger – and learning how to refuel accordingly – isn't important if you aren't good at recognizing hunger
in the first place. "A lot of people don't have a good sense of what
[true hunger] is," Anderson says. "There are folks who don't have a
coach or a plan [and think], 'Because of exercise, I should eat
something." But that's not a helpful mentality, particularly if your goal is weight loss,
experts say. "We know from all the research that people who try to lose
weight just by exercising are the least successful," Dugas says. "But
you need to exercise for your health." It's also a key strategy in weight maintenance after weight loss.
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