Fats in Trendy Diets
Posted by , MS, RD, CDE


There’s no doubt that eating fat isn’t the dietary taboo it used to be. For years, many registered dietitians and other healthcare professionals have been telling patients that the quality of fat is more important than the quantity of fat. Yet recently, with the surge in popularity of diets like Whole30 and ketogenic, consumers are wondering if all fat — and even as much as possible — is the smartest idea of all.



Whole30 requires followers to strictly avoid certain foods for 30 days. Gone are all grains, legumes, dairy products, alcohol, added sugars and sugar substitutes. If one bite or sip of banned food slips in, you’re back to day 1. Why avoid these foods? According to the Whole30 creators,[i] they are likely culprits in low energy levels, gut disorders, food cravings, seasonal allergies, aches and pains, blood sugar problems and more. By following the plan for 30 days, you’ll learn how different foods affect you. The creators of Whole30 promise that this diet plan is life changing.

Fats in the Whole30 eating plan come from a variety of sources.[ii] The plan encourages a high saturated fat intake with choices like fatty meats, coconut, coconut oil and ghee — the only dairy product permitted on the plan. Other encouraged fats are extra virgin olive oil, avocado, cashews, hazelnuts, macadamia nuts and olives. Peanuts are not permitted. Other nuts and seeds are permitted in lesser amounts. With careful attention, it’s possible for followers to limit saturated fats to the recommended less-than-10%-of energy level.

Ketogenic Diet

Ketogenic diets were originally developed to treat children with epilepsy who were refractory to drug treatment.[iii] Fasting appeared to improve symptoms, thus a diet which mimicked fasting was conceived. In the fasting state, the majority of energy comes from stored fats, with some coming from protein and very little from carbohydrates. Though ketogenic diets vary, they are frequently devised to be at least 80 percent fat, up to 15 percent protein and about 5 percent carbohydrate. Diets with the least protein and carbohydrate are the most difficult to follow but the most effective at reducing seizures. Each meal needs to be planned carefully because a deviation can take the individual out of ketosis. The exact mechanism of a ketogenic diet remains unknown, but theories relate to brain chemistry and energy production in the brain.

Today ketogenic diets are gaining popularity as a treatment for weight loss and type 2 diabetes. The American Diabetes Association stated that very low-carbohydrate or ketogenic diets may only be appropriate for up to four months, as there is little long-term research citing benefit or harm.[iv] According to the U.S. News Best Diet Report, a ketogenic diet provides more than 40 percent of calories from saturated fat[v] with common sources of fat being coconut oil and nut butters.

Working with Clients

Clients will continue to ask registered dietitian nutritionists (RDNs) about popular and trendy diet plans. Most plans have some wiggle room that allows us to help the client choose the most wholesome and health-boosting foods while minimizing less healthful choices. For example, even though Whole30 encourages bacon and sausage, RDNs can steer clients to eggs and fatty fish.

[i] https://whole30.com/whole30-program-rules/

[ii] https://whole30.com/downloads/whole30-shopping-list.pdf

[iii] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2902940/

[iv] http://care.diabetesjournals.org/content/41/Supplement_1/S38

[v] https://health.usnews.com/best-diet/keto-diet/health-and-nutrition