The keto diet is all about fat. This is, after all, an eating plan in which up to 80 percent of the total daily calories are supposed to come fromfat, so it is going to be the main nutrient you focus on most. But not all sources of fat are equally healthy.
“Many people boil it down too simply and think they just need to eat a lot of fat and avoidcarbs, but you can quickly eat an excessive amount of unhealthy fat on theketo diet,” saysKendra Whitmire, a nutritionist and dietitian with Sunshine Nutrition and Wellness in Laguna Beach, California, who practices functional and therapeutic nutrition.
Keto’s leap onto the scene as a trendydietis unique. “There’s never been a push for a high-fat diet before,” saysScott Keatley, RDN, of Keatley Medical Nutrition Therapy in New York City. As a result, 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 oversaturated fats, says Keatley, even though both are considered keto-friendly. Saturated fats can raise your LDL, or “bad” cholesterol, while unsaturated fats can help lower cholesterol levels, per theAmerican Heart Association (AHA).
These unsaturated fats have been shown to beanti-inflammatoryandheart-healthy. For example, in onestudy published in May 2020 in Cell, people following theketogenic dietfor eight weeks experienced a shift in thegut microbiomethat reduced inflammation. (Per apast review, the gut microbiome is a collection of bacteria, microbes, and other components in the gut that may affect various bodily functions such as immunity,metabolism, and disease risk.) Researchers noted this is likely due to the ketone bodies produced during ketosis, a state in which you burn fat for your main source of energy instead ofcarbohydrates.
That said, some of the research on the keto diet is conflicting. In a smallstudy, published in June 2019 in the journalObesity, switching to a keto diet was associated with higher inflammatory markers and cholesterol. More data needs to be accumulated to determine the effects that a keto diet, as well as the specific fats eaten, has on one’s health.
You can eat higher-fatfoods that containprotein, like bacon and sausage, but you’re better off adding fat to foods, as it’s easier to control, says Keatley. And bacon and sausages have a lot of calories, protein, andsaturated fat. If you go off keto and continue eating these while adding carbs back in, it’s likely that you’ll regain any weight you may have lost. What’s more, consuming a lot of saturated fat, something that’s easy to do when choosing these types of foods, increases your levels of LDL (“bad”) cholesterol. LDL cholesterol boosts your risk of heart diseaseand stroke, according to theAmerican Heart Association (AHA).
Also know that while pure sources of fat, such asolive oilorcoconut oil, contain 0 carbs, other sources, like nut butter oravocado, may be primarily fat but have carbohydrates that need to be counted in your total, too. Still, with research studies, like one published in January 2020 in the journalCirculation,showing thatcoconut oilconsumption leads to an increase inLDL (“bad”) cholesterol levels(which raise your risk for heart diseaseand should be limited), it’s more important than ever to choose the right types of fat — even on a fat-friendly diet.
A final guideline: Even if you’re on keto, portions of fat still matter, saysJill Gullotta, RDN, the founder of Jill Gullotta Nurition 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. After all, compared with protein and carbohydrates, fat is the more dense in calories. Also, considering that 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 minusfiberand sugar alcohols(since fiber goes through your system undigested). Both are taken into account here.
Consider this your guide to cutting through the fat.
