Here's What You Need to Know about Dietary Fat

saturated vs. unsaturated and polyunsaturated fat

Confused? Here's the Skinny on Fat

Dietary fat can be a confusing topic. USDA guidelines recommend limiting dietary fat to 30 percent of daily calories – a standard they’ve endorsed for decades -- to help lower the risk of obesity, cardiovascular disease and diabetes.

Sounds easy, right? If only nutrition guidelines were so easy!

Not everyone agrees with the nutritional guidelines put out by the USDA. The American Heart Association, for example, focuses more on the quality of fat, or type, rather than the quantity. And researchers from the European Society of Cardiology are asking for revisions to global dietary guidelines based on studies suggesting that fat may actually help prevent heart disease.

If you really want to get the skinny on fat, you have to look a little deeper than all fat – you need to look at the type of fat in question. And even that is a little confusing.

For example, cutting back on saturated fat – which health officials considered public enemy number one for decades – can reduce your cardiovascular disease risk by 17 percent, according to a systematic review by Cochrane. Indeed, the USDA guidelines recommend limiting saturated fat, which comes from sources like beef, pork, cream, butter and cheese, to just 10 percent of overall calories. On a 2,000-calorie diet, 10 percent is roughly 20 grams of saturated fat. The guidelines recommend avoiding trans fats, which are unsaturated fats found in partially hydrogenated vegetable oils and other processed foods, altogether.

(Again, not everyone is a fan of these recommendations—last year, three leading British cardiologists stoked controversy by suggesting that saturated fat does not, in fact, contribute to cardiovascular disease risk.)

Limiting fats are one issue. What you replace them with is another. According to research, replacing so-called “bad fats” (trans and saturated fat) with so-called “good fats” like polyunsaturated and monounsaturated fats, can have a positive impact on cardiovascular disease risk. But if you replace those fats with carbohydrates, the benefits disappear.

It may take experts a while to reach consensus how much saturated fat we should eat every day. But it’s still important to understand fat in its various forms and what current science says you should be eating. Here’s the skinny on fat.

Types of Fat: Good Fat vs. Bad Fat