Most health care professionals agree that diet and exercise work together when it comes to losing weight and keeping it off. However, carbs are an important source of energy for exercise, so you'll need to plan carefully to fuel your body for your workouts. While it might be tough training for a marathon on few carbs, you can limit carbs and exercise at the same time without ill effects. Just be sure to consult with your doctor beforehand about whether it's OK for you to work out on your low-carb diet plan.
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Carbs and Exercise
Carbs and exercise seem to go hand-in-hand. Carbs serve as your body's preferred source of fuel and, when it comes to exercise, provide the energy your muscles need to run, stair-climb and lift weights. Without enough carbs, you may not perform as well, according to the American College of Sports Medicine, and may not get the results you want. You should generally try to eat carbs one to three hours before your workout to get the fuel your body needs for a worthwhile workout. There is, however, some evidence that you can work out without having to load up on carbs.
Exercise on a Low-Carb Diet
In addition to carbs, your body also burns fat for fuel during your workout. However, depending on the exercise, you may not start burning that fat until you're about 30 minutes in. If your muscles don't have the carbs to use as energy, though, your body may be able to burn more fat instead, according to a 2014 study published in the Journal of the American College of Nutrition. This study looked at the effects of a low-carb diet compared to a low-fat diet on exercise in a group of overweight and obese individuals. The researchers found that the group following the low-carb diet burned more fat during exercise than the low-fat diet group. The researchers also noted that limiting carbs didn't seem to affect exercise ability.
Getting Enough Protein
When you're not getting enough carbs, you need to make sure you're getting enough protein when exercising, according to a 2007 article published in the American Journal of Clinical Nutrition. Protein helps ensure you're preserving your muscle and not burning it for fuel. Aim for 0.7 grams of protein per pound of body weight. For example, at 200 pounds, you'd want about 140 grams of protein a day. On your low-carb diet, protein comes from meat, poultry, eggs, fish, cheese, nuts and seeds. A 3-ounce portion of fish, meat or chicken has 22 to 28 grams of protein; one egg has 6 grams; and an ounce of cheese has 7.
Tips and Tricks
Due to the adaptation process that occurs when you're getting yourself into ketosis, you may not want to start exercising during those first few weeks of your diet plan, according to the authors of the 2007 article in AJCN. Your doctor may be able to tell you when it's OK for you to incorporate activity. Even on a non-ketosis-inducing low-carb diet, you should be cautious. Fatigue may set in early in your workout, which may affect performance and increase risk of injury. When adding exercise, start slow, monitor your progress and increase as your tolerance improves.
There's also concern about electrolyte balance, so you need to make sure you're getting enough sodium by adding a little salt to your food and enough potassium from potassium-rich veggies such as broccoli and spinach.
Fuel up one to three hours before you hit the gym, not just for energy needs but to avoid stomach upset that can be caused by eating too close to your workout. Adequate hydration is also necessary, so drink plenty of water throughout the day and 8 ounces 10 to 15 minutes before you exercise.
- American Journal of Clinical Nutrition: Low-Carbohydrate Nutrition and Metabolism
- Journal of the American College of Nutrition: Long-term Effects of a Very Low-Carbohydrate Weight Loss Diet on Exercise Capacity and Tolerance in Overweight and Obese Adults
- Academy of Nutrition and Dietetics: Timing Your Pre- and Post-Workout Nutrition
- American College of Sports Medicine: Pre-Event Meals
- University of Michigan School of Medicine: Timing is Everything: Why the Duration and Order of Your Exercise Matters
- Today's Dietitian: Protein Content of Foods
- American College of Sports Medicine: Selecting and Effectively Using Hydration for Fitness
- American Heart Association: Food as Fuel - Before, During and After Workouts