How Many Calories to Maintain Weight

Steve Silvestro, MD, DABOM, FAAP, is the Director of Clinical Product Strategy at Saluvia.

Here, we’ll dive into exactly what influences your body’s energy (or calorie) expenditure and offer guidance on calculating your daily calorie needs as an estimate for how many calories you should be eating to maintain your current weight.

Calories are a unit of measurement for energy. The words are often used interchangeably, as calories from food provide your body with energy to fuel everything from keeping your heart pumping to running a marathon. The amount of calories you burn per day is called your energy expenditure ( Popson, 2021 ).

You can’t calculate how many calories you need to maintain weight without first knowing your daily energy expenditure. A variety of factors influence how much energy you burn, but the three main categories are:

BMR refers to how much energy the body burns each day to maintain vital body functions at rest ( Sabounchi, 2013 ). Even when you’re sitting on the couch watching Netflix, your body uses energy to keep your blood circulating and your organs (like the heart, kidneys, and brain) functioning.

Body composition (i.e., how much fat mass vs. lean muscle mass you have) also impacts your BMR. Lean muscle mass burns more calories at rest than fat mass—everything else remaining equal. This means a leaner person will burn more calories at rest than a person of the same weight.

BMR is the largest contributor to your daily energy expenditure—accounting for around 60% of total energy (Popson, 2021).

Basal metabolic rate is an estimate of how many calories you'd burn if you were to do nothing but rest for a day.

The TEF refers to how much energy is needed to digest the food you consume, absorb nutrients from it, and convert some of those nutrients to energy while storing others. About 10% of your total daily energy expenditure goes toward these processes ( Howell, 2017 ). So yes, you even burn calories while eating!

TEF may be influenced by meal composition (protein tends to take more energy to digest than other nutrients) and the size of the meal, in addition to a person’s age and level of physical activity ( Calcagno, 2019 ).

The amount of physical activity a person gets is the most variable contributor to energy expenditure. For someone who is not very active, physical activity may only contribute 15% of daily energy expenditure, whereas it may contribute up to 50% for very active people. So, being more active requires more calories.

Age and sex also play a role in daily energy expenditure. Males tend to have higher energy needs, on average, than women, largely due to body size and having more lean muscle mass. BMR declines with age for both sexes ( Bredella, 2017 ; Moe, 2007 ).

As you can probably imagine, with so many factors affecting your daily calorie needs, this isn’t such a simple question to answer. But we can give you some guidelines.

The 2020 Dietary Guidelines for Americans provide target daily calorie intake ranges to promote a healthy weight, accounting for the factors described above as well as age and sex ( USDA, 2020 ). Remember, these are averages, so try not to get too hung up on these numbers.

Most adult women need between 1,800 to 2,400 calories per day. That range drops slightly after the age of 31 to 1,800 to 2,220 calories daily, and then to 1,600 to 2,000 for those 61 and older (USDA, 2020).

Men’s daily calorie needs are slightly higher than women's. This is due to generally higher body mass, and even at the same body weight, men (on average) carry more lean body mass than women. Most adult men 65 years of age and under need around 2,200 to 3,000 calories per day (USDA, 2020).

The ranges listed above are generalizations for the average population. They don’t account for your specific height or weight. To figure out your specific calorie needs, you’ll need to first calculate your BMR. To get started, you’ll first need to know your weight in kilograms (kg) and height in centimeters (cm).

BMR for males = (9.99 x weight in kg) + (6.25 x height in cm) – (4.92 x age) + 5