Get the facts straight on dietary fat

You might think that fat is a nutritional evil, but the truth is that in small amounts, it's essential to health. And not all fat is created equal. We'll go over the science surrounding different types of fat and what they can do for your body.

• Fats, oils, waxes, certain sterols, and esters all fall into the category of "lipids," which are substances that dissolve in organic solvent but not water.
• The term "triglyceride" is more specific and applies to fats and oils, which differ in their melting points. At room temperature, fats are solid, whereas oils are liquid.
• All fats contain the same number of calories by weight: about 250 calories per ounce or 9 calories per gram. Volume for volume, however, the calorie count can differ substantially. For example, 250 millilitres (1 cup) of oil weighs more — and therefore has more calories — than a cup of whipped margarine, because the air added to increase the margarine's volume has no calories. In addition, if the whipped margarine is one of the low-calorie versions, a considerable percentage of its weight will come from added water.
• A diet rich in high-fat foods results in more weight gain than a diet made up mainly of carbohydrates with some protein. Not only are fats a more concentrated source of calories than the other food groups, but studies indicate that the body is also more efficient at storing fats than carbohydrates and protein.

• It's important to distinguish between the fat you consume in foods and the fats circulating in your blood or stored as adipose tissue. Even if your diet contained no fat whatsoever, your body would still convert any excess protein and carbohydrates to fat and store them as such. Therefore, eating dietary fat isn't what creates bodyfat.
• When our weight remains steady, it's because we're storing and using fat at equal rates. If our food intake exceeds our need for energy, our bodies will synthesize more fat and we'll gain weight, no matter what the composition of our diet is.
• The average woman's body is about 20 to 25 percent fat by weight, and the average man's is 15 percent. The greater proportion of fat in women is an evolutionary adaptation to meet the demand for extra calories needed to bear and nourish children.
• Most body cells have a limited capacity for fat storage. The fat cells (adipocytes) are exceptions, as they can expand as more fat accumulates. An obese person's fat cells may be 50 to 100 times larger than those of a thin person. In addition, overweight infants and children accumulate more fat cells than their thin counterparts. Once in place, fat cells will never go away, although they will shrink if fat is drawn off to be used for energy production.
• There's a theory which hypothesizes that shrunken fat cells emit a chemical plea for replenishment, which could explain why many people spend their lives on a roller coaster of weight loss and gain.

At the end of the day, it isn't a good idea to eliminate fat from your diet entirely. Instead, try to consume more "good" fats, such as the kind found in fatty fish like salmon. This type of fat can actually lower you risk of heart disease. Nutrition is a complicated picture, but you can definitely make some positive changes by cutting out unnecessary fats from your diet.