Body fat

March 20, 2015 - Nutrition

Body fat: Why do we need it?

Our bodies need a certain amount of fat to function normally. Fat is essential part of our nerves, brain, cell membranes and spinal cord. Internal fat pads the kidneys and other organs, external fat protects against cold weather. Reference man has about 4 percent of body fat, or 6 fat pounds for a 150-pound man (2.7 kg for a 68-kg man). Reference woman has 12 percent essential fat-15 pounds for a 125-pound woman (6.8 kg for a 57 kg woman). Body composition is simply the ratio of lean body mass to fat body mass. Too much fat can lead to health problems like heart disease, diabetes, high cholesterol and other serious conditions. If you keep your body fat within a reasonable level, you’ll be healthier and, of course, slimmer.To increase or decrease your percent of body fat you need to create the right balance between the calories in and calories out. The best way to do this is to decrease daily calories by about 400-500 and increase your exercise. Aerobic exercise along with strength training is ideal.Some aspects of your body composition are genetic (where you store fat), but most fat increase is related to lifestyle.

Body Fat Categories for Women

Body Fat Categories for Men

What Is Body Composition

Body composition is the term used to describe the different components that, when taken together, make up a person’s body weight. The human body is composed of a variety of different tissue types including lean tissues (muscle, bone, and organs) that are metabolically active, and fat (adipose) tissue that is not.

Body Weight Measurements

Standard body weight scales provide a measure of total weight, but don’t determine the lean-to-fat ratio of that weight. Standing on most scales can tell you only if you weigh more than the average person, but not if that weight is fat or muscle. Based only on scale weight, a 250-pound athlete with 8% body fat may be considered “overweight” by a typical weight chart. Such charts are not a good indication of ideal body weight for general health or for athletic performance. There are a variety of ways to measure the amount of body fat a person is carrying.The most accurate way is ‘underwater weighing,’ which weighs the person on land and then underwater,But equipment for this is very expensive and not readily available.

Another fairly accurate option is Bioelectric Impedance Analysis (BIA). BIA consists of electrodes being placed on a person’s hand and foot while a current (which is not felt) is passed through the body. Fat has less water and is more resistant to the current, whereas muscle, which contains more water, is less resistant. The resulting numbers are entered into an equation which figures the percentage of fat and lean tissue.

The easiest method is measuring waist circumference and determining the Body Mass Index(BMI). A waist circumference over 35 inches for women and 40 inches for men is cause for concern.

Figuring BMI involves a little more calculation. BMI is done by multiplying your weight in pounds by 703, then dividing that number by your height in inches two times. If the end result is less than 18.5, the individual is underweight;18.5 to 24.9 is normal; 25.0 to 29.9 is overweight; and over 30 is obese.

However, you must be aware of this disclaimer. BMI alone is not an indication of body fat, especially in athletes and bodybuilders. Growing children under 18 years old should also avoid using BMI

One final way of determining body fat is using skin calipers to measure fat at specific places in the body. However, not only is it easy to make errors, but this method also doesn’t measure any interior fat or fat contained in thighs and women’s breasts.

Ideal Body Weight and Percent Body Fat

The ideal weight and fat-lean ratio varies considerably for men and women and by age, but the minimum percent of body fat considered safe for good health is 5 percent for males and 12% for females. The average adult body fat is closer to 15 to 18% for men and 22 to 25% for women.

Athletes tend to be at low end of this scale due to their increased lean weight (muscle mass). While low levels of body fat seem to be related to improved performance, body composition alone is not a great predictor of sports success. A linebacker needs to have enough body mass (lean and fat weight) to generate high forces and avoid injury. Body fat among elite athletes vary largely by sport. There is little evidence of any benefit when men drop under 8% and women drop under 14 percent body fat.

How Low Is Too Low?

While the average body fat percent in the United States and Europe is increasing, extremely low body fat percent is also a health problem.Women athletes who lose too much fat risk injury, decreased performance and health issues.

The female athlete triad refers specifically to three related health problems often found in women athletes:

How Much Body Fat Is Too Much?

Just as too little body fat can cause physiological complications, too much body fat is also harmful. For men over 25% and women over 32% fat there is a dramatic correlation with illness and disease.

Body fat and exercise

To lose body fat , you need to create a calorie deficit for the entire day(burn off more calories than you consume)Exercise can contribute to the calorie deficit but is overrated as a way to reduce body fat. Exercise is better used to prevent weight gain and to maintain weight loss. Also to relieve stress and boosts your metabolism. Many people do lose weight by adding exercise. That happens because they also subtracting some calories. Many others have lost no weight despite hours of working out. Reason is they are eating afterward generous amounts of calories that replace all they burned off. They may have exercise for 30 minutes, burned off 300 calories , but then they consumed 300 calories of “recovery food”in 3 minutes. If you do want to use exercise to promote weight loss, think about doing exercise that builds muscle. Unlike aerobic exercise that burns calories primarily during the exercise but very few thereafter, strength training boosts your metabolism throughout the entire day and night. Muscle tissue burns calories. The more muscles you have, the more calories you burn.