A Guide to Fats: The Good, the Bad and the Worst

Eating fat makes you fat, right?  Makes sense since dietary fat contains more calories per gram (9 calories/gram) than either carbohydrates or protein (4 calories/gram). And the more calories you eat, the more weight you gain.  Not exactly.  Eating calories from any source – fat, carbohydrate or protein – only leads to weight gain when more calories are consumed than burned off.

Fat’s Finer Qualities

Fat is an essential nutrient that provides and stores energy (it’s your body’s long-acting fuel source for low-intensity exercise). Dietary fat provides essential fat-soluble vitamins A, D, E, and K.  It also insulates and contours the body and surrounds and protects your kidneys, heart, and liver. Too little fat in your diet can lead to hair loss, tiredness, decreased concentration and slow-healing wounds.

Because your body needs fat, low-fat or fat-free foods aren’t always best.  Especially since sugar or salt is often added to these foods to make up for the missing creamy taste that fat provides.

Rather than run from fat, focus on finding the “right” fats on nutritional labels.

Here’s What to Look For:

Monounsaturated Fat:  GOOD

  • Reduces LDL “bad” cholesterol levels when eaten in place of saturated fats
  • Healthy sources:  canola oil, olive oil, peanut oil, nuts, olives, and avocados

Polyunsaturated Fat (includes omega-3 and omega-6 fatty acids):  GOOD

  • Reduces LDL “bad” cholesterol and increases HDL “good” cholesterol.  Makes you feel fuller so you eat less  and may prevent inflammation
  • Omega-3 is best: Healthy sources include fish (especially salmon, tuna, lake trout, halibut, herring, sardines, and mackerel), ground flaxseed, flaxseed oil, canola oil, and nuts (especially walnuts)
  • Healthy sources of omega-6: safflower, sunflower and vegetable oils, mayonnaise, salad dressing, and sunflower seeds


  • Large amounts may increase LDL “bad” cholesterol levels
  • Solid at room temperature.  Animal sources:  butter, lard, high fat meats (especially the skin) and high fat dairy products. Tropical plant sources:  palm kernel and coconut oil

Trans Fat: WORST – Avoid entirely

  • Raises LDL “bad” cholesterol and decreases HDL “good” cholesterol 
  • Found in stick margarine, solid vegetable shortening, and high-fat processed foods and commercially baked products

Reaching for the right fats may actually help you lose the wrong fat (the extra pounds around your waist).

Meet the Author

Carla J. Stevens, RD, is a Registered Dietitian and Board Certified Specialist in Oncology Nutrition at Aurora Medical Center and Vince Lombardi Cancer Clinic in Two Rivers, Wisconsin.

Read more posts from this author

The information presented in this site is intended for general information and educational purposes. It is not intended to replace the advice of your own physician. Contact your physician if you believe you have a health problem.

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