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Eating Fat for Athletic Performance and Weight Loss: Does it Help or Hinder?

By Amanda Turner MS, RD, CSSD - February 15, 2017

Fat is currently a big topic in the dieting and performance world. As an essential nutrient, it performs many necessary functions for our bodies. However, fad diets seem to argue strongly for or against fat either for weight loss or athletic performance. So, what’s the scoop?

The Role of Fat
Fat has many beneficial roles in the body. It acts as protection, helps with absorption of essential nutrients, is an essentially unlimited fuel source, aids in hormone production, aids in neurological development, aids with thermoregulation and best of all, adds flavor and increases the feeling of satiety after meals. Containing 9 calories per gram, it is the most dense macronutrient and doubles the calorie content of both carbohydrate and protein (both coming in at 4 calories per gram).  

Fatty acids are the building blocks of fat. Think of a fatty acid as a single Lego block, then think of a fat (like butter, avocado, or the fat in meat) as a Lego home. It would take lots of single Lego blocks to make that home. There are four different types of fatty acids: saturated, monounsaturated, polyunsaturated, and trans. The chemical structure of the fatty acid is what designates into which category the fat falls.

From small picture to the big picture of food . . . Foods typically contain multiples types of fatty acids. Going back to the Lego example, if saturated fat is a Lego block that is red, our Lego home that represents butter wouldn’t actually be all red even though we identify butter as a primarily saturated fat. Butter contains a blend of saturated and unsaturated fats, with more than 50% falling into the saturated column. So, your Lego home for butter would be more than half red Lego blocks, but you’d also see some yellow, blue and green blocks in there as well. . . . Are you following so far? To get even more complex, certain types of fatty acids within a group (i.e. saturated fats) have shown to have more beneficial health effects than others in the group proving to be harmful. This is why conversations around fat can be so incredibly confusing!

Health Effects of Fatty Acids
Research shows us that each fatty acid category has different health benefits. Although they are all calorie dense and help with satiety, they act very independently in the body. Here is what we know the health effects are from each category.

Monounsaturated Fats
-Increase HDL Cholesterol
-Heart Healthy


Polyunsaturated Fats
-Omega 3 types lower triglycerides and inflammation
-Omega 6 types increase inflammation and platelet aggregation


Saturated Fats
-Raise LDL Cholesterol
-May be Pro-Inflammatory


Trans Fats
-Raise LDL Cholesterol
- Lower HDL Cholesterol


Based on the types of fat you primarily consume, you can see that fat can either be really healthy for you or really harmful. In general, diets can have a varying amount of fat and still be healthy. Some individuals diets are as low as 20% of their total intake, whereas diets like the Mediterranean Diet can provide as much as 40% fat, primarily from mono and polyunsaturated fats. The type of fat seems to be what matters most. The American Heart Association recommends that individuals keep saturated fats < 7% of total calorie intake (<16g on a 2000 calorie diet) and avoid processed trans fats completely.  

Fat and Athletic Performance
For athletes, fat is a beautiful thing because it can help you (finally) feel full! Besides that, there is emerging research that eating more fat may make you a better fat burner which would theoretically help endurance athletes. This is true, if you eat more fat and less carbohydrate, you become more efficient at utilizing fat as a fuel source, BUT you also become less efficient at using carbohydrate as a fuel source. Is this beneficial? The limited research we have on this type of diet for endurance performance is inconclusive. It seems that some individuals feel and perform better on a higher fat diet while others see decreased performance.

It’s important to remember that carbohydrate metabolism by-products are part of the fat burning change. The term we dietitians use is “fat burns in a carbohydrate flame”. As part of endurance training, your body becomes more effective at using fat as a fuel source, especially in your long training (when you’re training correctly). As exercise becomes more intense, regardless of the type of your diet, you will utilize more carbohydrate stores. My concern as a sports RD is if an athlete is not at least consuming carbohydrates around their workouts, they will not have the glycogen stores in the muscle to fuel the intense ending of a race. Balance and timing is key for these nutrients.

Also, fat is the slowest digesting macronutrient, so higher fat contents both before and after training sessions can slow the delivery of carbohydrate and protein to the muscle. This could cause stomach upset during training if you have a high fat meal prior to your training, and it could delay muscle recovery post-workout. However, if you are feeling really hungry all day, every day during your training, fat can be extremely helpful to help keep you full.

Fat and Weight Loss
Reducing fat does not necessarily produce weight loss, but creating a calorie deficit does. You can do this with moderate amounts of fat in your diet. The key here is balance. Fat is a super calorie dense nutrient with nine calories/gram compared to four calories/gram for carbs and fat. Therefore, having a ¼ cup of almonds for 200 calories may not be as visually or volumetrically satisfying to you as having a full cup of cooked brown rice. However, you can lose weight on both as long as you are able to stick with the correct portions.

In my experience, individuals do best with weight loss when they feel like they’re eating a lot of food and are able to have items that taste really good. Fat provides the taste factor for a lot of folks. So, finding the balance between volume  (lean meats, veggies, fruits, whole grains) and taste/fat (oils, dressings, nuts/seeds, spreads, and cheese) is the key to a successful weight loss plan. In short, you can eat a high or low fat diet and still lose weight. However, you must be diligent with planning a hypocaloric diet in comparison to your daily caloric expenditure.


In short, fat is an essential nutrient and plays lots of very important roles in your body’s physiology. It is very calorie dense, which can lead to calorie overconsumption. The type of fat that you eat is indicative of overall health, where our current research points to plant fats > animal fats, and unsaturated fats > saturated/trans fats.  Olive oil, nuts, fatty fish are better than sunflower oil and soy oil which may be better than plant saturated fats like palm oil and coconut oil which seems to be better than meat fat, butter, cheese, and lard. Overall, I have to say that it seems our understanding of fat in it’s relationship to performance, weight loss and health is still in its infancy. I think there is much more to learn, especially from the perspective of how fat interacts with other nutrients in an individual’s diet.


American Heart Association:

Mediterranean Diet:

Low Carb High Fat Diets for Endurance Performance, Review:

Should Athletes Eat Fat or Carbs: