How many calories should you eat in a day: USDA guidelines for men, women, children

There is no single answer to how many caloriesyou should eat in one day as it depends on a number of variables, including gender, age, weight and activity level. (stock.adobe.com)

Few things are as essential as nutrition, yet few things can feel as nebulous. Even the question of how to lose weight is contested by experts, who say there’s more to it than just eating less and exercising more. 

How many calories should you eat in a day? There is no single answer to this question, either, experts say. It depends on variables including gender, age, weight and activity level.