Updated: Mar 24, 2020
This is a question that I get asked a lot, especially being a Sports Nutritionist. The answer isn't so black and white. There are many factors to consider when it comes to working out that makes the answer to this question a little tricky to navigate.
Today I'm sharing the details on the best options of when to workout and what is likely best for you!
Maybe you're a night owl...
And the only time that makes sense for you to workout is at the end of the day. Well, let me explain what happens with your hormones when you workout and why I don't usually recommend an evening sweat sesh: When you exercise, especially if it involves weight training or high intensity interval training (aka HIIT), your body increases it's cortisol (stress hormone levels). It does this for a very smart reason. Cortisol helps to increase your levels of blood glucose so that your muscles can gain access to energy so that it can run, squat, jump, and lift. Increasing your cortisol levels has another effect - it can inhibit your production of melatonin (sleep hormone). Raising your cortisol levels at night can cause your body to have disturbed sleep. This can translate to inability to fall asleep, waking up throughout the night, or having a low amount of time in deep sleep (where your major restorative actions occur). Considering that you need high quality sleep to recover from your workout and tap into your fat stores, this makes exercising at night not ideal.
So that leaves the morning
Or even the early afternoon. At least when it comes to your higher intensity workouts. In the morning, you naturally have higher levels of cortisol. Your body does this so that you can wake up and have energy to start your day. This is the perfect time to take advantage of your naturally high cortisol levels and get moving! Morning workouts - especially those in a fasted state) - increase your fat burning mechanisms and can assist in weight loss. Plus, studies show that exercise can increase energy levels and reduce fatigue - even if you have a chronic fatigue syndrome/disease!
If you can't workout first thing in the morning, then even a lunchtime walk for 20-30 minutes in the sun can have benefits. Studies show that just 15 minutes spent walking outside can significantly reduce your cortisol levels.
A final note on cortisol
It may seem like cortisol is the enemy for weight loss, but this isn't true. Like everything in our body, it serves a very important purpose. We use cortisol in states of emergency (think fight or flight) and to get that competitive edge during our workouts. Using our natural circadian rhythm to our advantage is key. Plus, making sure that we aren't elevating our cortisol levels throughout the day with excessive stress is extremely important. Cortisol is supposed to spike in the morning and decrease throughout the day. Keeping these levels high throughout the day (with things such as late afternoon coffees, evening interval training, and emotional stress) can cause your body to store blood glucose around your stomach and make it impossible to lose weight.
The topic of weight loss is clearly not as simple as calories in vs. calories out. Understanding your hormones, how food effects your body, your individual physiology, and emotional stressors are just a few factors that come into play with weight loss.