Diabetes Forecast

The Facts About Fats

How to tell healthy fats from unhealthy ones—and why it matters

By Madelyn L. Wheeler, MS, RD, FADA, CD , , ,


The nutrition recommendations from the American Diabetes Association in the past have focused on helping people manage their diabetes and avoid complications by reducing the total amount of fat in their eating plans. Based on evidence from recent studies, the current nutrition recommendations position statement (released online by the ADA in October 2013) provides a positive note about this misunderstood nutrient: “Fat quality appears to be far more important than quantity.”

Essentially, this means that the total fat in your daily eating plan should be higher in the types of fats that are considered healthy—monounsaturated and polyunsaturated fats—and lower in unhealthy fats—saturated and trans fats (more on those types later). Choosing the healthiest kinds of fat may benefit your blood glucose control and make it less likely that you’ll experience cardiovascular disease and other complications. While the amount of fat you eat appears to be less important than the quality, each person has different needs. The target for the total amount of fat in your eating plan should be individualized; a registered dietitian can help you set a target.

Healthy, high-quality fats from foods are necessary—they help us build cells and maintain brain function. Our bodies don’t make healthy fats, so we have to eat them in order to enjoy their benefits. Still, fat should be eaten in small amounts (keep reading—I’ll explain why).

How can I tell which foods contain healthy and unhealthy fats?

Every food with fat in it contains a mixture of saturated, monounsaturated, and polyunsaturated fats, which are also called fatty acids. The fatty acid it contains the most of puts a food in the category of healthy or unhealthy (see table, below). For a more complete list of foods in the healthy or unhealthy categories, see the ADA/Academy of Nutrition and Dietetics booklet Choose Your Foods: Exchange Lists for Diabetes ($3.25 including shipping; shopdiabetes.org).

What are healthy fats?

Fatty foods that are higher in monounsaturated or polyunsaturated fat are considered healthy because eating patterns  including them are associated with better blood glucose control and improved cardiovascular risk and risk factors, such as blood pressure andcholesterol levels. Plant-based fatty foods containing a majority of healthy monounsaturated fat include nontropical oils such as canola or olive (tropical oils such as coconut contain a large amount of unhealthy saturated fat). Sources of healthy polyunsaturated fat include avocados, seeds, and nuts such as walnuts. One animal-based type of food that contains a healthy fat (a type of polyunsaturated fat called omega-3) is fatty fish, such as salmon. The current recommendation for people with diabetes is to eat at least two servings of fatty fish a week because such fish can help prevent heart disease. Note that the fish itself should be fatty, not the way you cook it. Coating fish with batter and frying it in oil can add unhealthy fat.

What are unhealthy fats?

Fatty foods that are higher in saturated fat are considered unhealthy. Animal-based foods that have fat usually contain mostly saturated fat. These include fatty meats and full-fat cheeses and other dairy products, such as whole milk, sour cream, and butter. For health, the goal is to reduce saturated fats in the diet. Some ways to do this include:

  • Trimming the visible fat from meats before cooking or eating.
  • Not eating the skin or cracklings.
  • Rinsing cooked, still-hot ground beef with warm water and letting the liquid drain before using the meat.
  • Using lower-fat dairy products.
  • Cooking with small amounts of oil or cooking spray instead of butter or lard.

Eating less saturated fat will have a positive effect on blood lipids (fats in the blood), measured by lower LDL (“bad”) and higher HDL (“good”) levels in a cholesterol test.

Trans fats (found in baked goods, other processed foods packaged for long shelf life, and even some margarines) are a man-made kind of unhealthy fat. Food processors make them by adding hydrogen molecules to vegetable oils to make the oils more stable and solid. You’ll see such foods listed in the ingredient lists of packaged foods as partially hydrogenated oils. Try to avoid foods with any trans fat on the nutrition label or partially hydrogenated oils in the ingredients list. Trans fat raises total and LDL cholesterol, increasing the risk of heart disease.

Why eat fat “in small amounts”?

The problem with fats is that a small amount packs a lot of calories. Each gram of pure fat provides about 9 calories (each gram of pure protein or pure carbohydrate provides 4 calories). So to help people avoid eating too many calories, experts recommend eating healthy fats, but in small amounts.

Studying Fat

Nutrition recommendations for diabetes are based on scientific evidence from well-conducted studies. Types of studies include:

Observational studies, which can establish associations but don’t offer solid proof that one factor causes a change. An example is comparing weight gain over time for people who report eating breakfast and for those who say they don’t eat breakfast.

Randomized controlled trials that can prove cause and effect. For example, people in the study or experimental group are assigned to eat more of their daily fat in the form of monounsaturated fats than are the people in the control group. The strength of controlled trials is that participants are randomly assigned to the study or control group. That way, the results aren’t unfairly influenced by existing health, behaviors, or preferences.

When designing a randomized controlled nutrition trial of a food or a nutrient, ideally there should be only one change between the experimental and control groups. It is almost impossible to design a study that reduces only fat during a day, a week, or even a month because one or both of the other two macronutrients (protein and carbohydrate) would need to be increased to keep the overall calories the same. It is possible, though, to design studies that compare eating different types of fats.

Dairy Aisle

For milk, yogurt, sour cream, and cheese products with less fat, look for these terms on the label:




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