If you're watching your girlish figure, you probably already know to limit your fat intake. At nine calories per gram, fat contains more than twice the energy of carbs or protein, which each contain just four calories per gram. While there's no doubt that poly- and monounsaturated fats are healthier than their saturated counterparts, they still contain the same number of calories -- and are therefore just as fattening. Nonetheless, it's important to incorporate some of these "good" fats into your meals, even when you're dieting, because they help you feel satisfied after eating and help your body absorb nutrients.
Polyunsaturated and monounsaturated fats are the good guys of the fat world. While saturated and trans fats raise LDL cholesterol and contribute to heart disease, these unsaturated fats have the opposite effect. What's more, these healthy fats help control insulin levels, making you less susceptible to diabetes. Omega-3 fatty acids, which are polyunsaturated fats, go even further by possibly guarding against irregular heartbeats, reducing blood pressure and lowering your risk of coronary artery disease.
Weight gain is all about the mighty calorie. Eat more of them than you burn, and you're bound to pack on the pounds. Often, this gain is gradual -- a pound of fat equals roughly 3,500 calories, so you'd have to eat 500 more calories than you burn every day to gain a pound a week. When it comes to calories, your body does not discriminate. Depending on how much you eat, you could gain weight just as easily with low-fat foods.
Fats are an important part of your diet, but don't make them the main part. Twenty to 35 percent of your total calorie intake should come from fat -- and at least 90 percent of those should be mono- and polyunsaturated fats. Overall, half of your daily diet should consist of fruits and vegetables, about one-fourth should come from grains -- preferably whole ones -- and the rest should come from protein sources. These portions apply whether you aim to gain weight or lose it.
Healthy Fat Sources
You already know to eat polyunsaturated and monounsaturated fats, but the next step is to find foods that contain the stuff. Look to plant sources for most of your fats: avocados, nuts, seeds, olive oil and safflower oil are all good choices. Flaxseeds are excellent sources of omega-3 fatty acids, but they contain a type that's more difficult for your body to absorb. Seafoods such as salmon, anchovies and even algae have types of omega-3 that are more easily absorbed. In general, avoid fats that turn solid when cooled, such as lard, because these are usually saturated.
Nina K. is a Los Angeles-based journalist who has been published by USAToday.com, Fitday.com, Healthy Living Magazine, Organic Authority and numerous other print and web publications. She has a philosophy degree from the University of Colorado and a journalism certificate from UCLA.