Each January, millions of people make a New Year’s resolution to lose weight or eat healthier, or both. To achieve this goal, many people will undertake strenuous exercise programs that incorporate too much exercise too soon, resulting in fitness exhaustion or injury. Overtraining can actually keep you from losing weight.
As a health neuroscientist, I have been studying the brain and cognitive mechanisms underlying eating behaviors and the role exercise has played in helping people improve their diets for over 10 years.
Energy and exercise
The truth is, you just can’t walk away from a bad diet and expect to lose weight (if that’s your goal). Humans are very good at conserving energy and will count the calories burned during exercise by consuming more calories later in the day or by being less physically active for the rest of the day.
That being said, you can and should exercise to help you lose weight and maintain your weight loss. But not to compensate for the calories consumed.
If you are looking to lose weight, the only way to do it is to control your calorie intake. The most effective and efficient way to do this is to limit the consumption of ultra-processed foods, typical “junk food” and fast food meals. Even if you’re not trying to lose weight, cutting back on ultra-processed foods is good for both mental and physical health.
Regular exercise makes this task easier by improving brain and cognitive processes that help us regulate junk food intake and by reducing stress. Best of all, 20 minutes of brisk walking is enough to get the benefits.
Why we eat too much junk food
We know that we shouldn’t overeat candy, cookies, cakes and fries, or drink sugary sodas. Diets high in these ultra-processed foods cause us to gain weight. But they are so hard to resist.
Ultra-processed junk food was designed to be as tasty and rewarding as it gets. When we are exposed to advertisements in the media or to actual foods (for example, chocolate bars in grocery store checkouts), brain activity in regions associated with processing rewards increases. This reward-related brain activity leads to increased cravings and an urge to eat, even when we are not hungry.
A region of the brain known as the dorsolateral prefrontal cortex (dlPFC) helps us limit the intake of ultra-processed foods by decreasing activity in these reward regions to reduce cravings and initiating the cognitive processes needed to exercise. conscious control over food choices.
When using functional brain imaging to examine brain responses, neuroscientists have shown that increased activity in dlPFC helps us control cravings and select healthier foods by decreasing activity in areas reward of the brain. Conversely, when the activity in dlPFC is decreased, we have a harder time resisting the temptation to attract junk food and will consume more snack foods.
Exercise May Help Regulate Food Intake
Exercise stimulates brain plasticity, which is the brain’s ability to adapt its functions based on new data. Increasing brain plasticity makes it easier to change our habits and lifestyle. A growing body of evidence has shown that regular physical activity can increase prefrontal brain function and improve cognition.
These exercise-induced increases in prefrontal brain function and cognition make it easier to regulate or limit our consumption of junk food. And we can see the effects with as little as 20 minutes of moderate intensity exercise.
I have shown that people consume less ultra-processed foods like crisps or milk chocolate after 20 minutes of moderate-intensity exercise (in our study, this was a brisk walk at 5, 6.1 km / h on a treadmill with a slight incline). Research has also shown that just one high-intensity interval training session and a 12-week high-intensity aerobic exercise program can reduce preferences or appetite for high-calorie junk food. Similar effects are seen when people engage in moderate aerobic exercise or strength training.
The main takeaway here is that regular exercise can reduce the number of people craving junk food and improve their ability to resist the temptation to these enticing foods by improving brain function and cognition. This makes it easier to limit the consumption of these foods to achieve healthier eating and weight loss goals.
Exercise also helps reduce stress
When people are stressed, the body releases a hormone called cortisol, which activates what is called the fight-or-flight response. When cortisol levels are high, the brain thinks it needs more fuel, which leads to increased cravings for ultra-processed sweet or salty foods.
Participating in regular exercise or just one exercise session reduces perceived stress levels and cortisol levels. Exercise also helps reduce consumption of unhealthy foods and drinks when people are under stress.
Stress can also have an impact on the functioning of the brain. Research has shown that stress can lead to decreased activity in the prefrontal cortex and increased activity in reward regions of the brain when looking at images of food. This makes it harder to resist the temptation of alluring junk food.
By offsetting the impact of stress on prefrontal brain function, exercise makes it easier to maintain your goals of eating healthier or reducing junk food intake. Twenty minutes of brisk walking can help the prefrontal cortex recover from temporary changes in activity, such as those seen when people are stressed.
The next time you’re feeling stressed out, try taking a 20-minute brisk walk. It might keep you from stress eating.
Which exercise is the best?
Researchers are often asked what is the best exercise and how much to exercise.
Ultimately, the best exercise is the one you enjoy and can maintain over time. High Intensity Interval Training (HIIT), aerobic exercise, meditation and mindfulness, yoga, and strength training are all effective in helping improve diet by targeting prefrontal brain function and by reducing stress.
If you’re starting a new exercise routine this New Year, make yourself comfortable, be kind to yourself, listen to your body, and remember that a little goes a lot.
Study shows how the brain controls food cravings
Provided by La Conversation
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