Why you should eat before a workout
Before we begin, let’s get one thing straight: working out on an empty stomach is NOT the best way for everyone to lose weight. In fact, there are quite a few reasons why you should eat before a workout, no matter what your goals may be.
1) Working out on an empty stomach can actually make you hold onto fat. Several different mechanisms have been proposed to explain this phenomenon, but they all suggest that working out on an empty stomach can slow down your metabolism and limit the amount of fat you burn.
2) Working out on an empty stomach can lead to dehydration. When you’re dehydrated, your performance can suffer. In fact, many studies have shown that hydration status does affect physical performance.
3) Working out on an empty stomach increases the amount of cortisol in your body. This is especially important for people who are trying to lose fat because cortisol tends to prevent fat loss (more about this later).
4) Working out on an empty stomach may increase your desire for high glycemic carbs. If this is the case, you’ll end up craving fast digesting carbs when you’re done working out, which will rapidly turn into fat if it’s not used immediately.
All of these reasons have to do with hormones and metabolism. Since this is also the case for working out after eating, let’s take a moment to understand how some of these hormones work.
The hormone insulin has the primary job of shuttling nutrients into cells, so it’s no surprise that it plays a key role in weight loss. When your body is digesting food, whether it’s healthy or not, there are two phases of insulin secretion.
Phase 1 is called the ‘early phase of insulin secretion’ and its job is to shut down further food intake. This makes perfect sense when you consider that your body doesn’t want you eating more if it’s just eaten a bunch of calories.
The second phase, called the ‘late phase of insulin secretion’, is responsible for getting nutrients out of the blood and into cells.
In normal-weight people, Phase 2 insulin secretion occurs about 40-75 minutes after eating a meal. However, in obese people, this phase can be delayed by several hours which makes losing fat more difficult.
This delay also happens when you exercise on an empty stomach which is why doing so can cause you to hold onto fat. Let’s face it, if your body thinks it just ate a bunch of calories, there’s no reason for it to release the nutrients stored in your fat cells.
Even worse, this delay causes an increase in cortisol production which leads to insulin resistance. Insulin resistance is extremely common in people who are trying to lose weight because it makes losing fat much more difficult.
All of this means that eating something before your workout can help you lose fat by delaying the ‘late phase of insulin secretion’. This will prevent cortisol from increasing and make it easier for you to get nutrients into your cells where they can be burned.