Defining Low-Carb

• While low-carb diets come in many shapes and sizes, the elements discussed herein will be primarily seen with low-carb diets in which you are consuming less than 100 g of carbs per day. Thus, if your diet allows for a greater carb intake, although it may still be a reduced carb intake from your "normal" diet, it is not low-carb in the sense of these effects. Typical carbs include pasta, breads, processed foods, starches and sugars.
  
  

Low-Carb and Endurance

• Glycogen is an energy source that your body extracts and manufactures from carbohydrates. Your body normally uses glycogen for fuel during exercise anytime you are performing work at greater than 60 percent of your maximum heartrate. This means that your body will be first looking to glycogen during weight training and moderate to high intensity cardio. Unfortunately, your overall glycogen stores will be impaired during a low-carb diet, as carbs form the body's main supply of glycogen. Thus, while on a low-carb diet you can expect to have significantly less endurance in general.
  
  

Low-Carb and Strength

• A low-carb diet can also have an adverse effect on your strength limit in the gym. Due to the diuretic (water flushing) effects of a low-carb diet, your body will be less hydrated at any given time. As a good portion of the body's water is stored intramuscularly, this means that your muscles will lose their "pumped" look. In addition to affecting their appearance, hydration depletion will also affect your muscles' performance. You will not be able to exert the same level of intramuscular pressure as you otherwise would, thus affecting your maximum strength potential.
  
  

Induction Blues

• During the induction weeks (the weeks where your body is transitioning from using glycogen to using fat as a primary fuel source) of a ketogenic (a state where your body is primarily burning fat for fuel) diet, the resultant fatigue and brain fog can destroy your ability to perform a quality workout. These effects occur due to the body having depleted its glycogen stores without having made the switch to a ketogenic state. While this effect is transient, your inability to concentrate during this period can negatively impact your workout.
  
  

Considerations

• To avoid these effects, consider replacing your low-carb diet with a carb-cycling approach. On a carb-cycling approach, you feed your body carbs only on days that you are performing a substantial amount of exercise. This can help refill glycogen stores and rehydrate the muscles, alleviating the otherwise negative effects from a low-carb diet. Remember to eat mostly clean carb sources on these days--stick to fruits, vegetables and some whole grains.