Factors That Affect Body Fat

  • 2 Minutes Read

Why do some people have too much body fat? Is it just a question of eating too many calories and/or not exercising enough?

Factors That Affect Body Fat

Why do some people have too much body fat? Is it just a question of eating too many calories or is there more to it?

According to Dan Benardot, PhD, RD, FACSM in Advanced Sports Nutrition, 2nd edition there are 7 factors that play a main role in body composition:

1. Genetics. You can't change the genes you are born with - some folks are simply built to accumulate more or less fat. If you have a larger trunk, shorter legs/fingers, then chances are you are going to have a higher body fat than someone who has a long trunk, long legs/fingers. Genes can also affect where body fat accumulates as well. Genes predispose us to certain qualities but that doesn't mean we are destined to be overly fat.

2. Age. We are more likely to lose lean body mass and increase fat once we pass the age of 30. However, if we persist in regular exercise as we age, we can combat the creeping loss of muscle. Think "use it or lose it" with muscle and bone strength.

3. Sex. Women have a higher essential fat storage need (about 12%) than men (about 3%). Our hormones also affect where body fat is deposited (think pear vs. apple shape with excess weight).

4. Menopause. Decreasing level of estrogen is associated with decreasing energy expenditure - and that is in turn associated with higher body fat and lower lean body mass. Does this have to happen? Not necessarily - it could be mostly related to a decrease in moderate intensity activity and more sedentary time. See my blog post published 7/15/14 http://www.mynetdiary.com/weight-gain-during-menopause.html ).

5. Type of Activity. More aerobic activity is associated with lower body fat but any activity performed for long enough can burn calories and help lower body fat. Tip: If increasing lean body mass while reducing body fat is a two-pronged goal, then be sure to include weight resistance exercise to optimize muscle mass.

6. Amount of Activity. Exercising a great deal without sufficient calories intake can cause a large loss of muscle mass in addition to lowering body fat. Benardot recommends a modest decrease in food calories in the presence of athletic training: only 10% - 20% below maintenance. For instance, if 2500 kcal supports your weight (including exercise calories), then your calories intake would only drop by 250-500 kcal. That means an intake goal of 2000-2250 kcal to help nudge a reduction in body fat.

7. Nutrition. If you eat too many calories relative to total calories burned, your body will store excess energy as body fat. If you eat too few calories, you could promote loss of both lean body mass and body fat. Will type of excess macronutrient (fat, carbs, protein, or alcohol) affect where fat is deposited? More research will help us answer that question. For instance, higher consumption of sugar sweetened beverages was associated with higher organ fat (visceral adipose tissue) - this was just published by Ma et al. in the Journal of Nutrition.

If you are interested in reading about BMI (Body Mass Index) vs. body fat, then read Ryan Newhouse's blog post published 7/26/11. Ryan's post includes body fat percentage norms and body fat testing methods.

Tip: The highest health risk occurs when there is excess body fat around your waist, especially near your organs (also called "visceral fat"). A big waist is likely a red flag for high visceral fat. Tracking can help you curb calories intake while also encouraging more activity - this can help you lose weight. Losing weight, over time, will help you reduce the dangerous visceral fat.

Weight Loss->Body composition
Jul 29, 2014
Katherine Isacks
Katherine Isacks, MPS, RDN, CDCES - Registered Dietitian and Certified Diabetes Care and Education Specialist (CDCES)

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