Both a hundred years ago and now, there were recommendations for distributing calories across nutrient groups.
Here are the 1921 recommendations:
An ideal distribution of the calories is one-tenth protein, three-tenths fat and six-tenths carbohydrate. In a dietary of 2400 calories this would be 240 protein, 720 fat, and 1440 carbohydrate.
The New Cookery (1921) by Lenna Frances Cooper
And, here are the 2021 recommendations (Actually they were published in 2015, but they are the most current recommendations.):
The Dietary Guidelines for Americans (USDA, 2015) recommend that an adult’s total daily calories come from the following:
- 45–65 percent carbohydrates
- 10–30 percent protein
- 20–35 percent fat
Some nutritionists recommend a ratio of 40 percent carbohydrates, 30 percent protein, and 30 percent fat as a good target for healthy weight loss.
A 1,500 calorie diet with 40 percent carbohydrates translates to 600 calories per day from carbs. Using a ratio of 4 calories per gram (g) of carbs, a person on this diet would need to eat 150 g of carbohydrates per day.
This 1,500 calorie diet would also include 450 calories or 112 g of protein, and 450 calories or 50 g of fat per day.