Granola or Protein Bars

These might seem like a good idea before you hit the gym, but there’s no clear definition of what they really are. Check the labels -- both kinds can have lots of sugar. If they do, your body will burn through that fast, and you may not get much else.

High-Fiber Vegetables

Your body needs fiber, but not before a workout. Vegetables like broccoli, Brussels sprouts, or cauliflower can be hard to digest and could make exercising uncomfortable. Stick with veggies that are easier on your system, like well-cooked asparagus or potatoes.

High-Fat Food

Not all fats are bad for you. But foods that have a lot of any fat can be a bad idea if you’re about to be active. Things like red meat make your body work hard to change their fat to energy. That can make you tired before you even get started.

Yogurt

As with protein bars, you’ll need to read the label carefully. Certain brands can be surprisingly high in sugar and fat, neither of which is good for your workout. And if you don’t digest dairy easily, a stop at the gym can make things worse.

Smoothies

These sound great in theory as a way to hydrate and get nutrients at the same time. But in practice, they can be less than ideal. Some are packed with sugar and will give you only a short burst of energy before the dreaded “crash.” And depending on what’s in it, a single smoothie can have as many as 800 calories.

Flaxseed

This seed has all sorts of potential health benefits -- some people use it to try to ease constipation or lower their cholesterol level. But it’s high in fiber and fatty acids, which aren’t what you want before a workout. So when adding it to your diet, pay attention to when you have it.