If you want to lose weight---specifically fat---it would seem that you should limit fat in your diet. Fat is only one of three major macronutrients that make up the human diet, and some is necessary to keep your system running smoothly. When it comes down to it, your overall energy intake, in the form of calories, plays the biggest role in your ability to lose, gain or maintain weight.
Features of Weight Loss
Calories represent how much energy a food provides. Consume 3,500 calories less than you burn to lose one pound. Fat is often a central concern when considering calories because, as macronutrients go, it is the most calorically dense. While carbohydrates and protein contain four calories per gram, fat contains nine calories per gram. Cutting out fat seems like it would be a simple way to reduce caloric intake and thus lose weight, but it is not quite that easy.
Importance of Fat
The body needs some fat to stimulate hormone production, facilitate the absorption of certain vitamins and to provide insulation for internal organs. Fats are also a source of energy for the body and take longer to digest than carbohydrates, so they contribute to sensations of satisfaction and satiation. Fats are found in most proteins, dairy and some plant sources.
Types of Fat
Although you need some fat in your diet, not all kinds of fat are equally desirable. Saturated forms of fat, largely found in animal products, contribute to weight gain as well as other health conditions, says the American Heart Association. In a 2003 Australian study published in the British Journal of Nutrition, lead author L.S. Piers said swapping saturated fat with monounsaturated versions induced a significant loss of body weight, even though participants did not significantly change caloric or fat intake. Avoiding trans fats will also help with weight loss. A Wake Forest University study led by Kylie Kavanagh and published in a 2007 edition of the journal Obesity found that monkeys fed a diet high in trans fats, despite it being a calorically controlled diet, gained significant weight---particularly in their bellies.
Effects of Low-Calorie Diets
Reducing your overall caloric intake has been shown to be the most effective method in losing weight. A randomized clinical trial performed by the Harvard School of Public Health and Pennington Biomedical Research Center of the Louisiana State University System, compared four different diets over a two-year period. The results, published in a February 2009 issue of the New England Journal of Medicine, demonstrated that regardless of a diet's macronutrient make-up, reducing calories results in weight loss. The trial's 811 participants ate either a low-fat/average protein, low-fat/high protein, high fat/high protein or high fat/average protein diet. Each diet followed nutritionally sound principles, focusing on unsaturated fats, whole grains and produce. All participants succeeded in losing similar amounts of weight and in reducing waist circumference, leading researchers to conclude that a total reduction in calories is the key to weight loss results.
As long as you limit your intake of saturated fat and eliminate most trans fats, your total intake of fat should be of less concern than your total caloric intake when you try to lose weight. For health purposes, it makes sense to follow American Heart Association guidelines of consuming 25 to 35 percent of your total daily calories from fat, with only 7 percent of those fat calories coming from saturated sources. Because reduced calories impact weight loss, keep track of your fat intake, as fats are more calorically dense than other macro-nutrients. Accent your meals with small servings of healthy fat---sprinkle nuts over your oatmeal, drizzle a teaspoon of olive oil on your salad or add a slice of avocado to your sandwich.
- Harvard School of Public Health: Diets That Reduce Calories Lead to Weight Loss, Regardless of Carbohydrate, Protein or Fat Content
- British Journal of Nutrition: Substitution of saturated with monounsaturated fat in a 4-week diet affects body weight and composition of overweight and obese men
- Obesity: Trans Fat Diet Induces Abdominal Obesity and Changes in Insulin Sensitivity in Monkeys