A former Army officer and reservist emailed me to ask about low-carb diets. Here is his question:
"Will a low-carb diet hurt my PFT scores?"
He went onto state that his unit was being called for active duty and he had to lose some weight to get into "fighting shape" so he went on one of the high protein and low carbohydrate diets and lost over 20 lbs very quickly. However, his workouts such as running, lifting weights and calisthenics were not that impressive and he is not seeing the results he needs.
The low-carb diet eliminates foods such as fruits and vegetables loaded with fiber, minerals, and nutrients vital to excretion and fighting illnesses. It is never a good idea to completely eliminate such an essential element of good health. Limiting unhealthy carbs (sugars) is always a good idea, but not eating key nutrients will definitely affect your workout.
If you are running fast to score a competitive time on your PFT, or doing calisthenics for maximum scores, the body needs carbohydrates for fuel. If you do not have this quick burning fuel in your body, you WILL fatigue more quickly. Some experts say that lifting weights, performing calisthenics, and running at a fast pace could increase the risk of muscular injury IF your glycogen level (stored carbs) is low.
I have recommended people who are extremely overweight to start a low-carb diet like Atkins or the South Beach Diet but only temporarily since they were too heavy and bloated to really move, much less try to run. These diets allowed them to lose more than 20 pounds of fat and retained water in a few weeks by eliminating carbs and going into ketosis.
However, by simply adding a gallon of water a day to your diet and eating fewer salty foods, your body will lose the excess water being retained. I have seen many under-hydrated people simply add water to their diet and have the same results of 20 pounds weight loss.
So the short answer to a long explanation - yes - having low levels of carbohydrates in your diet will affect your PFT test taking and your everyday workouts. If you want to lose weight, do it by reducing calories in and increase calories burned by more cardiovascular and strength training or calisthenics. Also check out my free diet plan - full of ideas on water intake, food varieties, and exercise tips.
Take a look at the "Physical Fitness Test Anxiety" article for tips to taking the PFT and recommended foods to help with performance. If you have any questions feel free to email me.
Stew Smith is a former Navy SEAL and fitness author certified as a Strength and Conditioning Specialist (CSCS) with the National Strength and Conditioning Association. If you are interested in starting a workout program to create a healthy lifestyle - check out the Military.com Fitness eBook store and the Stew Smith article archive at Military.com. To contact Stew with your comments and questions, e-mail him at firstname.lastname@example.org.