This question has two very different answers and depends on your personal muscle and fat ratio, your exercise goals and the intensity of your workout. Speaking very generally, our bodies need fuel to exercise and burn calories. The energy in our bodies is converted and used to fuel us through the workout.
What fuel are you going to use? There are three places that offer our bodies energy: sugar in our bloodstream, energy stored in our body tissues (lean muscle) and stored energy (body fat).
In the same way that a car needs gas to make a journey, you need to use body fuel to both exercise and do one of three things: maintain your body ratio of muscle and fat, reduce stored fat and maintain muscle mass, or increase muscle mass and decrease stored fat.
The ideal time to have snacks before a workout
Some nutritionists and health enthusiasts recommend having an easily digestible snack about 45 minutes before you work out. This means that you will have energy in your system to power your workout, and you will use that energy before your body uses stored energy. For professional athletes and people who train their bodies, on a regular basis, it is essential to fuel up before a workout. Otherwise, they risk losing lean muscle mass.
In case of weight loss, it’s different
However, if your aim is to lose weight (stored fat), scientists recommend not eating in the four hours leading up to a workout. This is general advice and follows the principle that your body will have to use stored energy, as there is less sugar available in your bloodstream. Be sensible, though, and consider what your workout is going to be. Please be brutally honest about your fitness level too.
Being overweight puts a strain on your heart and going all out on the treadmill for 20 minutes may leave you feeling faint and will do you more harm than good. A steady hill climb walk will burn body fat and is a better option if you are carrying extra weight. If you are planning a long workout, a small snack may be needed. The rules are not hard and fast but relative to your own exercise goals and body mass index.
Types of snacks
What type snack should you have if you need to fuel up before a workout? You need to choose healthy, easily digestible proteins, carbohydrates and fats — depending on your calorie needs as a whole. Your snack choices also need to be calorie-wise relative to your particular eating plan. Are you following a low-carb diet? If so, you could choose a low-carb smoothie with protein and healthy fats. Whip up a bowl of overnight oats and add chia seeds. Greek yogurt with berries is also a good choice. A snack of peanut butter and carrots provide healthy protein, fat, and fiber.
Remember that eating before a workout is a sensible choice if you are looking at maintaining or increasing your muscle mass. It is not recommended if you are exercising to get fit and lose weight. Evaluate the energy needs you must have for your planned session, consider the intensity and make sure you are fueled up for a successful workout.