Fat is a tricky macronutrient. We can thank the 1990s for the notion that eating fat will make you fat. On the other end of the spectrum, keto followers embrace fat and eat more than their fair share.
Either way, there are a multitude of misconceptions about fat floating around the internet and social media. Many people are surprised to learn the Dietary Guidelines for Americans recommend that about 20 to 35 percent of daily calories should come from fats.
But for runners, eating too much fat at the wrong times can be a nightmare on the gastrointestinal (GI) system. So how do you balance the need for fat without getting too much of it? Below, we delve into what science and nutrition experts have to say about fat—and how much you should eat per day—so you don’t have to.
More From Runner's World
The Different Types of Fat
The reason fat gets a bad reputation is because there are harmful fats: saturated and trans. But there are also helpful fats: polyunsaturated and monounsaturated. The difference in these types of fat boils down to chemistry. All fats consist of a chain of carbon atoms bonded to hydrogen atoms. In a saturated fat, the carbon atom is fully “saturated” with hydrogen. Unsaturated fat, on the other hand, does not contain as many hydrogen on the carbon chain.
Saturated fat is found primarily in animal foods, such as red meat, poultry, whole milk, cheese, butter, and even coconut oil. Unsaturated fat, on the other hand, comes from fatty fish and plant foods, like nuts, seeds, avocados, and most oils.
The science behind these molecules isn’t quite as important as the research that’s been done on these differing types of fats. While the jury is still out on whether or not saturated fat alone causes heart disease, a meta-analysis by the American Heart Association states that replacing saturated fat with unsaturated fat can reduce the risk of developing cardiovascular disease.
In addition, trans fats are created when hydrogen is added to liquid oil to transform it into a solid fat. Food manufacturers previously used this inexpensive type of fat in processed foods, but it’s since been outlawed in the United States due to health risks.
How Much Fat Should You Eat in a Day?
Ideally 20 to 30 percent of your total daily calories should come from fat, according to Angie Asche, M.S., R.D., C.S.S.D., owner of Eleat Sports Nutrition. She adds that you can approximate fat needs as 1 gram per kilogram of body weight (or 0.45 grams per pound).
For the average 2,000 calorie diet, that’s 400 to 600 calories from fat (44 grams to 66 grams). In a normal day, that’s like eating the following:
- ½ avocado (11 grams fat)
- 1 to 2 tablespoons olive oil (14 to 28 grams fat)
- 1 tablespoon peanut butter (8 grams fat)
- 1 cup low-fat plain Greek yogurt (5 grams fat)
- 4-ounce chicken breast (6 grams fat)
- 1 tablespoon chia seeds (4 grams fat)
Jenna Braddock, R.D., C.S.S.D., founder of Make Healthy Easy and the Off Season Athlete, agrees. “This is a big range and allows runners to play with the amount of fat in their diet to achieve their energy needs,” she says.
Both dietitians note that it’s important to prioritize unsaturated fat and minimize saturated fat to 10 percent or less of total daily calories. According to Braddock, “the essential [omega-3] fatty acids, EPA and DHA, are particularly important to focus on because of their well-known benefits on health and physiology,” such as boosting your heart and brain health, and preventing certain cancers.
That said, it’s entirely possible to overdo it on fat. “Eating too much of any macronutrient could lead to an excess amount of calories or unwanted weight gain,” says Asche. She adds that increasing fat above the recommended range could result in offsetting carbohydrates and/or protein, which could negatively impact both performance and exercise recovery.
When Should Runners Eat and Avoid Fat?
Eating healthy fats throughout the day to reap its many health benefits—such as reducing inflammation and muscle soreness, keeping blood pressure in check, and increasing oxygen uptake—is encouraged, but Asche recommends keeping fat to a minimum about an hour before a training run. Fat has more calories per gram than carbohydrates and protein (9 calories per gram, compared to 4 calories per gram), meaning that it takes longer to digest. Any fat that is left in the stomach during a run can cause GI disturbances.
In addition, Braddock suggests limiting fat considerably in the 24 hours leading up to a race, and proposes experimenting with when you eat different sources of fat in relation to your training runs.
With the rise of low-carb, high-fat diets, like keto, some runners have been experimenting with them in an attempt to train their bodies to use fat as fuel. The research on fat adaptation for exercise is still relatively new and limited, and the general consensus on how it affects performance is mixed. While a study in elite race walkers suggests that although you can train the body to use fat as fuel, it may negatively affect overall performance, other research in runners suggests it may be beneficial.
For instance, a study on male endurance athletes found that twelve weeks of keto-adaptation enhanced body composition, fat oxidation, and certain measures of endurance performance. Another study of 20 elite ultra-marathoners and ironman distance triathletes determined that those who were keto-adapted used a much higher rate of fat as fuel, with no differences in glycogen depletion, as compared to the high carb group.
Again, these studies were done on a very small, narrow range of participants, and personal results may vary. More research is needed. That said, with a diet like keto, 80 percent of your calories from fat and almost zero come from carbs—which is the fuel source your body and brain like to tap into first since it’s the fastest acting and most easily accessible. In other words, loading up on fat probably won’t do your long runs, speedwork, and HIIT workouts any favors.
[The 2021 Runner’s World Calendar features gorgeous photos, monthly motivation, and tips to inspire your running all year long.]
How to Incorporate Fat into Your Daily Diet
Tallying up how much fat you’re eating throughout the day can seem overwhelming. So rather than logging every single piece of food you eat, try to incorporate some sort of healthy fat at every meal. Keep in mind that the serving sizes for fat are smaller than carbs and protein. Here’s an example of a daily meal plan with plenty of healthy fats:
Breakfast: Asche suggests adding 1/3 of an avocado, or 1 to 2 tablespoons of almond butter to your toast, or 1 ounce of crushed walnuts or pumpkin seeds to your oatmeal to get your share of healthy fats during breakfast.
Snack: Make your own energy balls with ingredients like nut butter and seeds. These tahini maple oat balls have unsaturated fat from the tahini and flax seeds.
Lunch: Whip up a leafy green salad with tons of veggies, a protein of your choice, 1/3 of an avocado, and 1 to 2 tablespoons of olive oil.
Dinner: Asche recommends a salmon fillet with a salad tossed in olive oil. (Or you can add olives as a topper instead.)
Natalie Rizzo, MS, RD is a New York City-based dietitian, food and nutrition writer, national speaker and owner of Nutrition a la Natalie, a sports nutrition practice. She developed a love for cooking, nutrition and fitness as an adult, which prompted a career change from advertising to nutrition. She spends most of her spare time running along the NYC waterfront and creating (and photographing) healthy and tasty recipes.