Understanding the Nutritional Difference: Why do males generally require more calories than females when at rest?

October 25, 2025 •

4 min read

According to the Better Health Channel, an average man has a Basal Metabolic Rate (BMR) of approximately 7,100 kJ per day, compared to an average woman's 5,900 kJ, which illustrates why do males generally require more calories than females when at rest. This difference stems from fundamental biological factors that affect how the body burns energy.

Quick Summary

Males typically have a higher basal metabolic rate (BMR) than females due to greater lean muscle mass and larger average body size. Hormonal variations, particularly the role of testosterone, also influence energy expenditure, leading to higher resting caloric needs in men.

Key Points

Higher Muscle Mass: Males typically have more lean muscle tissue, which is metabolically more active and burns more calories at rest than fat tissue.
Larger Body Size: The average male is larger and heavier than the average female, meaning their bodies require more energy to maintain basic functions.
Hormonal Influence: Higher testosterone levels in men promote muscle development and elevate metabolic rate, while estrogen in women contributes to fat storage, which has a lower metabolic demand.
BMR as the Foundation: Basal Metabolic Rate (BMR) represents the energy needed to sustain life at rest; due to the factors above, an average male's BMR is higher than an average female's.
Individual Needs Vary: While general trends exist, an individual's specific caloric needs depend on their unique body composition, age, and activity level, not just gender alone.

The Core Concept: Basal Metabolic Rate (BMR)

The basal metabolic rate (BMR) is the amount of energy your body needs to maintain its most basic, life-sustaining functions when at rest. This includes essential processes like breathing, circulating blood, cellular growth, and hormone regulation. The BMR is the largest component of your total daily energy expenditure and is the primary factor explaining the difference in resting calorie requirements between the sexes.

Several elements contribute to an individual's BMR, and while genetics and age play a role, the most significant factors explaining the male-female disparity are body composition, body size, and hormonal activity.

The Primary Driver: Higher Muscle Mass

Muscle tissue is metabolically more active than fat tissue, meaning it burns more calories to sustain itself, even when the body is sedentary. Men, on average, have a higher percentage of lean muscle mass and a lower percentage of body fat than women. This is a key reason for their higher BMR.

Think of the body as an engine. A larger engine with more powerful parts (muscle) will naturally require more fuel (calories) to idle than a smaller, less powerful engine (fat). For example, a study in young adults found that men had significantly more skeletal muscle mass than women, both in absolute terms and relative to body weight. This anatomical difference directly translates into a higher resting energy burn for males.

The Influence of Average Body Size

On average, adult males tend to be taller and heavier than adult females. A larger body simply has more tissue and cells that need to be maintained, which requires a greater expenditure of energy. This means that even before accounting for differences in muscle mass, a larger person will generally have a higher BMR than a smaller person. The larger organs and overall body mass of an average male contribute significantly to their elevated resting calorie needs.

Hormonal Differences Affecting Metabolism

Sex hormones also play a crucial role in regulating metabolism and body composition:

Testosterone: More abundant in males, testosterone promotes the growth and maintenance of muscle mass and bone density. This hormonal influence directly contributes to a higher BMR. Higher testosterone levels are linked to lower body fat and better metabolic health in men.
Estrogen: More prevalent in females, estrogen is linked to fat storage, particularly in the lower body (gynoid fat). The body's tendency to store fat more readily, especially in preparation for childbearing, leads to a more conservative energy expenditure compared to males. Hormonal fluctuations during menstruation, pregnancy, and menopause also impact a woman's BMR.

A Comparative Look: Male vs. Female Caloric Factors

To better understand the distinct caloric requirements, consider the typical body composition differences:


Factor	Males (Average)	Females (Average)
Skeletal Muscle Mass	Higher, accounting for more of total body weight	Lower, making up a smaller portion of total body weight
Body Fat Percentage	Lower, often distributed in the abdominal area (android)	Higher, often stored in the hips and thighs (gynoid)
Average Body Size	Generally taller and heavier, leading to more tissue to maintain	Generally shorter and lighter, with a smaller overall mass
Metabolic Rate	Higher BMR due to muscle mass and size	Lower BMR influenced by higher body fat and hormonal factors

Beyond the Average: Personalizing Your Diet

While averages provide a general understanding, individual needs can vary widely. An elite female athlete with significant muscle mass, for instance, may have a higher BMR than a sedentary male. The key takeaway is to consider these general physiological differences, but always personalize nutritional plans based on an individual's unique body composition, activity level, and health goals.

Several formulas can estimate BMR, such as the Harris-Benedict equation, which takes into account gender, weight, height, and age. These tools can be useful starting points, but for the most accurate and personalized nutritional guidance, consulting a healthcare provider or a registered dietitian is recommended. The National Academy of Sports Medicine (NASM) offers a simple guide to calculate Total Daily Energy Expenditure (TDEE) by multiplying your BMR with an activity factor.

Conclusion

In conclusion, the primary reason why males generally require more calories than females when at rest is a higher average proportion of metabolically active muscle mass, a larger overall body size, and the metabolic effects of sex hormones like testosterone. These biological distinctions lead to a higher basal metabolic rate in men compared to women. Recognizing these fundamental differences is crucial for understanding general nutritional guidelines. However, for precise dietary planning, it is essential to consider individual body composition, activity levels, and other personal factors to create an effective and healthy nutrition strategy.

Learn more about basal metabolic rate and its calculation at the Cleveland Clinic.

Frequently Asked Questions

BMR is the amount of energy (calories) your body needs to perform fundamental, life-sustaining functions when you are completely at rest. It accounts for the majority of your total daily calorie expenditure.

On average, the basal metabolic rate for adult males is higher than for females. For example, some estimates suggest the average male BMR is around 1,696 calories, while the average female BMR is about 1,410 calories.

Yes, it is possible. A female athlete with a higher proportion of muscle mass and a lower body fat percentage may have a higher BMR than a sedentary man of the same age and weight.

Sex hormones significantly influence metabolism. Higher testosterone levels in males promote muscle mass, which boosts metabolism. Estrogen in females promotes fat storage, which is less metabolically active, contributing to a lower BMR.

All other factors being equal, a higher BMR means more calories burned at rest, which can lead to faster initial weight loss for males when consuming the same number of calories as females. However, weight loss is complex and depends on many other variables like diet and activity level.

The gender difference in caloric needs is more pronounced at rest. While physically active men still generally require more calories due to their higher muscle mass and larger average size, the activity level becomes a much more significant factor in determining total daily energy expenditure for both sexes.

BMR can be estimated using formulas like the Harris-Benedict equation, which factors in your weight, height, age, and gender. For example, the formula for males is BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years).