What Are the Best and Worst Fats to Eat on the Ketogenic Diet
The keto diet is all about the fat. And in an eating plan where up to 80 percent of the calories come from fat — which shifts your body into ketosis, or a state in which you burn fat for your main source of energy (instead of carbohydrates) — it’s going to be the nutrient you focus most on. But some picks are healthier than others.
“Many people boil it down too simply and think they just need to eat a lot of fat and avoid carbs, but you can quickly eat an excessive amount of unhealthy fat on the keto diet,” says Kendra Whitmire, a nutritionist and dietitian in Laguna Beach, California, who practices functional and therapeutic nutrition.
Keto’s leap onto the scene as a trendy diet is unique. “There’s never been a push for a high-fat diet before,” says Scott Keatley, RDN, of Keatley Medical Nutrition Therapy in New York City. Meaning: Research on choosing fats in the context of a high-fat diet is scarce.
What’s clear is that sources of unsaturated fat are still recommended over saturated fats, says Keatley, even though both are considered keto-friendly. These unsaturated fats have been shown to be anti-inflammatory and heart-healthy.
You can eat higher-fat protein foods, like bacon and sausage, but you’re better off adding fat into foods, says Keatley, as it’s easier to control it this way. And bacon and sausages have a lot of calories, protein, and saturated fat. If you go off keto and continue eating these while adding carbs back in, it’s likely you’ll regain the weight.
Also know that while pure sources of fat, such as olive oil or coconut oil, contain zero carbs, other sources, like nut butter or avocado, may be primarily fat, but also have carbohydrates that need to be counted in your total.
A final guideline: Even if you’re keto, portions of fat still matter, says Jill Keene, RDN, in White Plains, New York. “How much you specifically eat depends on your calorie needs and goals, but overconsuming fat can cause weight gain,” she says. Also, considering fat is your body’s main fuel source on a keto diet, she advises spreading out your fats evenly throughout the day.
Many people on a keto diet count “net carbs,” which are total carbs minus fiber (since fiber goes through your system undigested). We take both into account here.
Consider this your guide to cutting through the fat.
The 5 Best Fats to Eat Plenty of on the Ketogenic Diet
Though technically a fruit, avocados offer a rich source of heart-healthy monounsaturated fatty acids (MUFAs). They’re also packed with fiber to bolster digestive health. One-half of an avocado contains 161 calories, 2 grams (g) of protein, 15 g of fat, 9 g of total carbs, and 7 g of fiber (bringing it to 2 g of net carbs), notes the U.S. Department of Agriculture (USDA).
2. Olive Oil
“We know that when we have fats in our diet like MUFAs, they not only fill us up but keep cholesterol levels lower,” says Keatley. Olive oil is great for light sauteing, using in dressings, or drizzling over cooked meats or vegetables as a finishing oil. One tablespoon (tbsp) offers 119 calories and 13.5 g of fat, only 2 g of which are saturated fat, according to the USDA.
3. Avocado Oil
Like olive oil, avocado oil is rich in anti-inflammatory MUFAs, but the benefit to using avocado oil is that it stands up to high-heat cooking. For instance, the popular brand Chosen Foods says its avocado oil has a smoke point of 500 degrees F. According to the USDA, 1 tbsp of avocado oil has 124 calories, 14 g of fat, and 0 g of carbohydrates.
4. Nuts and Nut Butter
Nuts may offer unsaturated fats, but they also contain carbs, so look at the label to calculate exactly what you’re getting, says Whitmire. As an example, 1 tbsp of almond butter has 98 calories, 3 g of protein, 9 g of fat, 3 g of total carbs, and about 1.5 g of fiber (equaling about 1.5 g of net carbs), per the USDA. And, the USDA also notes, a 1-ounce (oz) serving of almonds (23 almonds) has 164 calories, 6 g of protein, 14 g of fat, 6 g of carbohydrates, and 3.5 g of fiber (totaling about 2.5 g net carbs).
5. Chia Seeds and Flaxseed
Whitmire recommends these because they offer omega-3 fatty acids. “Getting more of these fats will improve the ratio of omega-6s to 3s you consume, which some research suggests optimizes health,” she says. For example, an article published in September 2016 in the journal Open Heart cited research that linked consuming more omega-3s and fewer omega-6s (which are high in Western diets) to a lower risk of insulin resistance — the hallmark of type 2 diabetes — and obesity, among other protective health benefits. The USDA says 1 oz of chia seeds has 138 calories, 5 g of protein, 9 g of fat, 12 g of carbs, and a whopping 10 g of fiber (so only 2 net carbs). And also according to the USDA, 1 tbsp of ground flaxseed has 37 calories, 1 g of protein, 3 g of fat, 2 g of carbs, and 2 g of fiber (basically 0 net carbs). Just be sure to buy ground flaxseed so your body can absorb their omega-3s.
The 4 Fats You Should Limit on the Keto Diet
A slice of cheese contains 115 calories, 7 g of protein, 9 g of fat (5 g of saturated fat), about ½ g of carbohydrate, and no fiber, per the USDA. The saturated fat qualifies it as a food you ought to limit, but some research suggests the food has health benefits as well. A meta-analysis published in December 2017 in the European Journal of Nutrition found that cheese eating was associated with a 10 percent lower risk of heart disease and stroke, particularly for those consuming about 1.5 oz (or a slice and a half) per day.
Adding heavy cream or half-and-half to your coffee is one way to get an additional source of fat into your day, says Keatley. Just realize that it is a source of saturated fat — and, given the small serving size, it’s easy to go overboard. According to the USDA, 1 tbsp has 51 calories, 5 g of fat (3.5 g saturated fat), and is just shy of ½ g of carbohydrate.
3. Coconut Oil
Given that coconut oil is trendy, it’s been credited as a panacea for health ills — and given the general go-ahead to consume as much as you want. That’s not exactly the case. “There’s a controversy with coconut oil because of its high levels of saturated fats, which are the ones that clog arteries,” says Keene. But the argument some make is that coconut oil is different. Part of its fat is made up of medium-chain triglycerides, fatty acids that the body metabolizes quicker and are less likely to get stored by the body as fat, she says. That said, the USDA indicates that 1 tbsp has 121 calories, 13 g of fat (11 g are saturated fat), and 0 carbohydrates. Eat healthier unsaturated sources of fat first, and moderate amounts of these saturated sources, says Keene.
“Eating a significant amount of butter has some of the worst effects on your health compared with other fats,” says Keatley. It’s okay to use butter in your fat rotation, but best not to make it your go-to fat; instead opt for more unsaturated sources. Per the USDA, 1 tbsp of butter has 102 calories, 12 g of fat (7 g of which are saturated fat), and 0 carbohydrates.
The Worst Fat You Could Eat on the Keto Diet
Everyone — not just those on a keto diet — should stay away from consuming added trans fats. While these are naturally found in some meat and milk (though you’re probably avoiding milk on keto because of its higher carb count), according to the USDA, they’re often added to processed foods. “If you’re eating a lot of packaged products, you’re probably getting more trans fats than you think you are,” says Keatley.