**Before I begin, I am not a Nutritionist or Registered Dietitian. It's my personal belief that all Certified Personal Trainers should educate clients on nutrition, but not prescribe any detailed numbers. Information here is meant for understanding of physiology, but not to provide any recommendations for an individual's daily dietary intake.**
Low carb diets began to blow up in the 1990's when the Atkin's Diet became popularized in media. Basically it said you could lose a bunch of weight if you had a high protein and fat diet, while excluding carbs. Here is the problem with low carb diets:
To begin, weight loss is strictly by calories, not type of calorie. If you consume more calories than you burn, you will gain weight. If you expend more calories than you consume, you will lose weight. It's as simple as that when talking about weight loss. It doesn't matter if you eat carbs, fats, or protein; weight control is strictly by caloric intake and expenditure.
Then why were people doing low carb diets losing weight? If you take away carbs, you can take away calories. For example, a person eating 150 grams of carbohydrates and 90 grams of protein per day is eating more calories than a person eating 0 grams of carbohydrates per day and 160 grams of protein per day:
- protein and carbs each have 4 calories per gram (we're not including fats in this example, but FYI it's 9 kcal per gram of fat)
- Person 1 = (4 kcal * 150 grams carbs) + (4 kcal + 90 grams protein) = 960 calories
- Person 2 = (4 kcal * 160 grams protein) = 640 calories
- For person 2, 70 extra grams of protein is equivalent to a 12 ounce steak
Fore weight loss, it would be better to eat all macronutrients in normal percentages, but decrease the total amount.
Energy is especially important for active people. Although calories can cause weight gain, calories count as energy. From the example above, Person 2 will lose weight, but will also have less energy.
Also, carbohydrates are important for muscle and brain function. Glycogen is the stored form of carbohydrates in the body. We use this glycogen to move our muscles. We replenish glycogen by eating more carbohydrates.
Protein on the other hand, is supposed to be used for muscle repair for growth. As we exercise or move throughout the day, our glycogen stores get depleted. When we need more energy and run out of carbohydrates, our body converts protein into glycogen to keep us going. If protein is being used for energy, it is not present to help us rebuild our muscles for strength and performance gains.
Sources of Carbohydrates
There are many different sources of carbohydrates and a few different types. Below is a link to read more about it, and also linked is a lengthy but great video about energy and nutrition. Let us know if you have any questions by hitting the comments!
Greater info on carbohydrates
Pre-Workout Nutrition and Energy
Baechle, T. R. & Earle, R.W. (2008). Essentials of strength training and conditioning 3rd Edition. Champaign, IL: Human Kinetics.
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