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:
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.”
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.
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.
To better tune into your hunger, pause before digging in, drink a glass of water and rate your hunger on a scale of one to 10, Crandall suggests. Aim to eat slowly until you reach a five, six or seven. “[You] want to be satisfied,” she says. It’s also important to make sure you actually like your workouts: Research shows that when people choose their exercise type, they eat less overall – and eat less unhealthy foods – at their next meal than people assigned to a particular workout. Elsen, who’s lost 30 pounds over the past two years, finds a similar concept holds true with diet. “If you’re making it really difficult on yourself … where you can’t live your normal life, you’re never going to maintain it,” she says. “Slow and steady wins the race.”