This article is all about body fat: how you get it, where it’s stored, what routes it takes to get there, and why this might be important to understand for purposes of weight loss or body shaping.
You will need to follow a little biochemistry and physiology, but nothing that’s too complex.
About Body Fat
First things first. Body fat is a natural substance. We all carry some body fat because it is essential to life and energy processes as well as being a source of hormones and other substances like essential fatty acids that we need to sustain life. The problems start to occur when we store too much body fat. Young lean men average out at 5-15% body fat and young women in the range of 15-25%. As we age, fat levels tend to increase. Some men and women (especially women) can carry more fat and still be metabolically normal. Active athletes can be in the lower range of body fat levels and professional male bodybuilders may measure as low as 5% body fat.
FAT IN FOOD, FAT FROM FOOD
We obtain fat from our diets in two ways.
1: Fat is consumed as a distinct proportion of most diets. This is the saturated and unsaturated fats from animal and plant foods such as fatty meats, dairy and cooking oils.
2: Our bodies can convert excess energy to fat. This is a much-overlooked source of body fat. If we eat in excess of our energy needs, our bodies convert the other main nutrients like carbohydrate and protein to fat, which is then stored when not used for energy. That’s why we get fat if we eat too much of anything.
When you hear the word “triglyceride,” with reference to metabolism, this is another word for fat that circulates in the bloodstream and in storage. Triglycerides are often measured with cholesterol when you doctor checks on your heart and cholesterol levels. Too high a level of triglyceride in the blood is a risk factor for heart disease and diabetes.
Metabolism of Fats
When you eat fat (triglycerides), enzymes break it down into the fatty acid portion and the glycerol portion for digestion and absorption across the intestines. Triglycerides are then reformed for transport to body tissues for energy or storage. Triglycerides are again broken down to fatty acids when required for energy production. The lipase enzymes do most of this management of the digestion and metabolism of fats.
Carbohydrates, which provide glucose on digestion, can be turned into fat when body stores of glucose are full. This process is called “de novo lipogenesis” which means “fat forming.” Protein can’t be turned directly into fat, but some protein can be converted to glucose when consumed in excess, and then be subject to fat forming in the usual way. It’s a process designed over millions of years of evolution, and designed to store energy in times of abundance (body fat) for use later in times of need.
Body fat is stored in tissue just under the skin (adipose storage), and in other less healthy places like the liver and internal organs (visceral storage).
Fat for Energy
The fatty acids component of fat are an essential part of our energy systems. Fatty acids are “burned” for energy along with glucose for just about all of the activities we undertake in proportion to intensity. More glucose is used at high exercise intensity, and more fat is used at lower intensity. However, overall, you don’t need to exercise at low intensity to burn fat and lose weight. It all evens out and energy (calorie) expenditure in movement is the main objective.
What You Need to Know About Fat Storage and Burning
1: Excess dietary fat, and protein and carbohydrate is stored as body fat.
2: Protein uses more digestive energy (thermic effect) and is not stored unless it is converted to fat along the way, while fat has most calories per gram and takes the least amount of digestive energy. Carbohydrate is in between.
3: Excessive body fat can cause diabetes and heart disease by disrupting fat metabolism.
4: You don’t have to target body fat specifically with exercise activity; just ensure you perform sufficient exercise volume to achieve significant energy expenditure, which will result in body fat burning.