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Secret Side Effects of Exercising Before Breakfast, Says Science

Sweating at first light may be the best decision you make all day long.

The early bird gets the worm, but what does the early-morning exerciser get? A lot, apparently. Working out before breakfast isn't just a great way to hit your fitness goals first thing in the morning—some research has associated the practice with unique benefits that you might not get by working out at other times of day.

Before we dive into those benefits, some caveats must be noted. Many studies exploring exercise and time of day are limited to small human trials or mouse studies—meaning that their conclusions aren't necessarily definitive. Additionally, lots of the findings are conflicting. "The research is all over the map on the best time to exercise, mainly because research is looking at all different types of benefits from stress management to weight loss and body composition," Bronwyn Bacon, ND, shared with ACE Fitness. Depending on your body, your goals, and the type of exercise you love, you may see lots (or zero) benefit to switching up the time of day you work out.

All of that is to say: The best time of day to work out is the one that works best for your schedule. If you're not a morning person, forcing yourself out of bed to hit the pavement before you've had coffee is hardly conducive to a sustainable fitness routine. But if you're an early riser—or are interested in shaking up your fitness—there are some potential benefits to working out before breakfast for your health, your mood, and more. Read on for what they are, and if walking is your exercise of choice, don't miss The Secret Cult Walking Shoe That Walkers Everywhere Are Obsessed With.

You might get better results from your workout

woman runner tightening shoe lace

Your body might have more strength and endurance in the morning to handle cardio. A 2013 review of research found that people's aerobic endurance may be greater in the morning, and that they tend to hit a higher heart rate during morning workouts than during evening ones. And for some exercise moves you should ignore at any time of day, don't miss The Worst Abs Exercises You Shouldn't Do After 40.

It will help wake you up

woman sweating and tired after exercising a workout

Your body's levels of cortisol—the "stress" hormone that impacts our energy levels—are naturally higher in the morning, and tend to slough off throughout the day until bedtime. Moderate-to-high intensity exercise can also (temporarily) elevate cortisol levels. By working out first thing in the morning, when your cortisol levels are already elevated, you give yourself an extra spurt of caffeine-free energy that can help power you through the morning.

It may help burn fat 

asian female group doing namaste yoga pose in row at the yoga class

If weight management is one of your fitness goals, consider prioritizing the morning workout. A small 2015 study found that men who exercised before breakfast enjoyed increased fat oxidation (aka the burning of internal fat stores for energy) compared to people who did their workouts at other times of day. A 2016 review of studies also found that exercising in a fasted state—such as in the morning before breakfast—tends to burn more fat than exercising after eating a meal with carbohydrates. However, the researchers note that it's unclear if these effects persist in the long-term.

You'll sleep better

Pretty young woman on bed in modern apartment smiling after wake up

Remember how we said that exercise early in the day boosts your cortisol and energy levels? Mastering your workout in the a.m. may also help you sleep better at night, because your body will have plenty of time to come down from its cortisol "high" before bedtime. Research supports this: A small 2014 study found that people who worked out on the treadmill at 7 am enjoyed deeper sleep than those who did the same treadmill workout later in the day. Some research also suggests that resistance exercise in general is associated with improved sleep quality—do it in the morning and you might get extra sleep-promoting benefits. And for more great exercise advice, don't miss The One Major Side Effect of Walking Every Day, According to Science.


Jessie Van Amburg
Jessie Van Amburg is a freelance writer and editor who has covered health, nutrition, and lifestyle topics for top media outlets including Women's Health Magazine,, and Well+Good. Read more about Jessie