Aerobic exercises such as walking use carbs and fats to fuel your activity.
Exercises are divided into two types: aerobic and anaerobic. Each type uses a different fuel source as your body converts the foods you eat into energy for your workout. Aerobic activities use two different types of fuel. Fat is primarily used when your heart rate is elevated into your training zone and it gives you the ability to sustain your session.
At the beginning of an aerobic workout, your body relies on carbohydrates for fuel. With sustained activity, your body then shifts to burning fat.
Fuel with Carbohydrates
At the beginning of your aerobic workout, your body converts carbohydrates into fuel. Carbohydrates are easily changed into fuel and are the most immediate energy source your body has. There is a limit to your carbohydrate storage, so this energy system doesn't last long. In most people, carbohydrate fuels approximately 90 seconds of activity. Plus, when you participate in aerobic exercise and bring in lots of oxygen, your body can use a different source of fuel.
Burn the Fat
In the presence of adequate oxygen coming into your body, fat is converted to fuel. Your aerobic activities are performed at a level that doesn't leave you out of breath; therefore, your oxygen intake is sufficient. The more efficient your body becomes through aerobic exercise, the easier it is for your body to convert fat into fuel. Fat allows you to sustain your workouts for a long duration to see weight loss, cardiovascular and stress-reducing exercise benefits.
Follow Workout Guidelines
Your aerobic workouts should last between 30 and 60 minutes to burn fat as fuel. The American College of Sports Medicine says shorter durations such as 10 minutes performed three times a day are also enough to burn fat. Aim to increase your duration as your fitness level improves. Your intensity level is one that lets you carry on a conversation, but unable to sing. Complete your aerobic workouts at least five days a week, with a goal of exercising on a daily basis.
Fuel Up Your Fit
During exercise, your body turns into an energy-burning machine - and you may need pre- and post-workout snacks to help you recover. Eat a light snack with carbohydrates before a workout for energy. Try a banana with a tablespoon of peanut butter, or a half-slice of whole-grain bread with hummus. After your workout, focus on protein to promote muscle rebuilding. A classic protein shake works, of course, but so does chicken breast with sweet potatoes or eggs on toast.