Beware of full-fat dairy. High in fat and calories, milk, sour cream and other dairy products can be a danger to your diet. Thankfully, there are a slew of low-fat and non-fat alternatives that won't seriously affect your bottom line. Most of the time you won't be able to taste the difference and if you do, your taste buds will likely adapt to the transition over time. Some food for thought: One cup of whole milk contains 160 calories, while a cup of low-fat milk has 90 calories. Low-fat dairy products, like milk, yogurt and cheese, have been shown to be super diet aids if you're trying to lose weight or maintain weight loss. Chalk it up to the calcium, protein or just rich taste, but consuming three servings of low-fat dairy per day seems to help dieters lose more. But are there certain populations who actually need full-fat dairy products? Yes - children under the age of two need full-fat dairy products to maintain the energy needed for rapid growth. Underweight children and teens also might be encouraged by their doctors to consume more full-fat dairy products. Some studies have shown that people who consume full-fat dairy gain less weight over a period of years than those who consume low-fat or fat-free dairy - some experts say the high-fat varieties are more satisfying; therefore, people may eat less. Another study showed that women who were trying to conceive decreased their risk of infertility by 25 percent, simply by consuming full-fat dairy instead of low-fat. Weigh the options - but keep dairy in your diet.