If you are a woman who has attempted a diet and exercise program with your spouse or significant other, you most likely have been frustrated about a few things. First, he eats MORE than you, exercises LESS than you, but still manages to lose TWICE the weight! Second, he doesn’t focus on the food choices he is making — he simply eats “a little bit” less. Finally, he doesn’t “feel” as hungry as you, so he is FAR less miserable by the end of the day. What are you doing wrong? Most likely, nothing. This is just one of those issues that can be chalked up to human biology and muscle physiology!
The fact that we, as men, burn more calories than women is no secret and a fairly simple concept to grasp. In general, men are taller, heavier, and have more muscle tissue than women due to natural hormonal differences from birth. Males actually begin to produce gonadal testosterone at about the sixth or seventh week of gestation, which has an immediate effect on our heart rate and respiratory rate. This predisposes men to have a higher basal metabolic rate (BMR) before we even leave the womb.
As men mature, we build and support more muscle tissue that sits on a larger, broader bone structure. After puberty, testosterone levels are about 15 times higher in men than women. As a result, the average 18-year-old male will have about 50% more muscle mass and half of the amount of total body fat than females of the same age. Since lean mass is our most metabolically active tissue, it becomes obvious that calorie requirements between men and women are not equal. Would you expect a half-ton diesel truck to get the same gas mileage as a Toyota Prius? It just doesn’t make sense.
What does this have to do with weight loss?
BMR is only one piece of our metabolic rate (MR). BMR is our resting energy expenditure. It’s the number of calories needed to keep your body alive and perform basic functions like breathing, keeping your heart beating, and maintaining body tissues. Men have a BMR of approximately 200-300 calories higher (depending on age) than women of the same height and weight. But when you add activity, this difference in energy requirement and expenditure is even higher. Because men naturally maintain a higher amount of muscle tissue, two people (a male and female) can perform the same mode, intensity, and duration of exercise BUT a male will burn a greater number of calories, due to his increased metabolic demands. One hour of exercise for a female may equal 450 calories burned, whereas that same hour of exercise could equal about 700 calories burned for a male.
Because of these differences, it can seem easier and more manageable for men to put ourselves in a calorie deficit and lose weight if our metabolic rate is 3500 calories/day, I still would be able to consume 2500 calories/day and lose 2lbs of fat mass each week. By making smart choices and spacing meals out correctly, 2500kcal/day would be enough to keep me satisfied with minimal hunger levels. If you are a female with a metabolic rate of 2200 calories/day, you would have to decrease calories to 1200/day to lose the same amount of fat mass. Even when making GREAT food choices, 1200kcal/day can be a difficult task. I know, I hear you, that’s not fair!
Other Factors Out of Your Control
Other functions that play a role in altering a female’s BMR include:
1. Menarche – when a woman begins her menstrual cycle, she will experience an increased basal caloric requirement of 100-300 calories/day.
2. Pregnancy – during pregnancy a woman will have approximately a 200-300 calorie/day increase in BMR requirements.
3. Breast Feeding – while nursing a baby, a woman will need about 400-600 calories/day more than normal to stay in calorie balance.
These factors all INCREASE BMR. But here is the problem: when these needs are no longer present, continued intake of these calories will lead to a gain in body fat. Also, if these increased calorie demands are not met with a proper balance of protein, fat and carbohydrate, they can contribute to excessive hunger, which causes overeating.
Because of these ever-changing circumstances in women, they will experience inconsistencies not encountered by men when setting weight loss goals.
One function of our genetic make-up that greatly influences BMR is our total body surface area. This is a reflection of your height and weight. The greater your body surface area, the higher your BMR. Taller individuals naturally have a higher BMR. Since there is nothing you can do to alter your height, you are stuck with this blessing OR restriction from birth.
What to Focus On
When attempting to lose body fat, do not compare yourself to others. We all have very different lifestyles, genetics, habits and predispositions. This means your “game plan” to lose 10lbs may be COMPLETELY different than your peers of the same age.
Figuring out the proper calorie intake (through tracking calorie intake) and a realistic exercise frequency (what does your schedule allow?) for YOU as an individual is the best way to ensure a successful action plan for yourself and all of your fitness goals.