Since protein provides 4 calories per gram, if your goal is to consume 20 percent of your calories from protein you’d need to eat 400 calories, or about 100 grams, of protein per day when consuming a 2,000-calorie diet.
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Carbohydrate Requirements. The Institute of Medicine recommends adults consume 45 to 65 percent of their daily calories from carbohydrates. Since carbohydrates contain 4 calories in each gram, calculate your carb requirements by dividing 45 to 65 percent of your calorie needs by four.
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Protein and carbohydrates each contain 4 calories per gram. Consuming the right balance of protein, carbohydrates and fat can help you maintain a healthy weight and optimize your energy levels. Protein and carbohydrates both contain 4 calories per gram, while fat provides 9 calories per gram.
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1 gram of carbohydrate has 4 calories. 1 gram of protein has 4 calories. 1 gram of alcohol has 7 calories. 1 gram of fat has 9 calories.
http://www.answers.com/Q/How_many_calories_does_a_gram_of_carbohydrate_have
Calories in Carbs. Each gram of carbohydrates contains 4 calories. If a food label lists the food as having 10 g of carbohydrates, then it contains 40 calories from carbohydrates.
http://www.livestrong.com/article/303715-how-many-calories-equal-a-carb/
Carbohydrates have 4 calories per gram, so 20x4 = 80 calories.     (Fat grams have 9 calories each, and Protein also has 4 calories). 19 people found this useful. Edit.
http://www.answers.com/Q/How_many_calories_does_a_gram_of_carbohydrate_have
1gram carbohydrate= 4 calories   fat=9 calories   protein=4 calories. 7 people found this useful.
http://www.answers.com/Q/How_many_calories_does_a_gram_of_carbohydrate_have
Nutrition labels list the volume of carbohydrates, fat, and protein in a food, rather than the calories derived from these nutrients. In order to ascertain how many calories come from carbohydrates, you need to know the calories per gram of carbs.
http://www.livestrong.com/article/303715-how-many-calories-equal-a-carb/
Each food contains a different amount of energy. All calories supply your body with the same amount of energy, regardless of the type of food from which they come. For example, fat calories have the same amount of energy as protein calories. Carbohydrates are macronutrients that contain sugars. Potatoes, rice, sugar, syrup, honey, fruit, vegetables, whole grains, nuts, seeds and legumes all contain carbohydrates.
http://www.livestrong.com/article/303715-how-many-calories-equal-a-carb/
Since fat provides 9 calories per gram, calculate your fat needs by dividing 20 to 35 percent of your calorie requirements by nine. Based on these recommendations you should eat 400 to 700 calories from fat, or about 44 to 78 grams of fat, each day when following a 2,000-calorie diet.
http://healthyeating.sfgate.com/gram-protein-carbohydrates-contains-many-kilocalories-5978.html
how many calories does one gram of carbohydrate have
One gram of carbohydrate has 4 calories.