In a recent column, I stated, “Even if we entirely avoided all carbohydrates, our bodies would use protein in an alternate recipe to make glucose (sugar) to fuel our cells.”
A reader in Ontario, Canada, responded: “According to Dr. Jason Fung, author of “The Obesity Code,” if one eats a diet of 65 percent healthy fat, 35 percent protein, and 5 percent carbohydrate, the body will be in ketosis and will burn fat, not protein, to make glucose to fuel our cells. Only when the body reaches the level of 4 percent fat will protein be used to make glucose.”
This reader then goes on to describe his success with this diet under his doctor’s supervision. “I have lost a pound a week for 15 weeks and feel very good after the initial few days of sugar withdrawal. My regime of full fat yogurt and milk, unsweetened whipped cream in my coffee, olive and avocado oils, limited fruit, no root vegetables, no flour, beans or pulses satisfies my hunger as no other diet has. Have you looked into the ketogenic diet? I believe it is revolutionary.”
I applaud your progress. And yes, I have looked into the research on ketogenic diets. Here are my thoughts:
Glucose — the primary fuel for our brain, muscle and other body functions — is easily provided by carbohydrates (sugars and starches in most plant-based foods). In the absence of carbohydrates, our amazing bodies can make glucose from fat and protein. Ketogenic diets severely restrict carbohydrates to force the body to manufacture glucose from these alternate sources. This causes acids (ketones) to build up in the blood — a condition called ketosis. In times of starvation or low-carb dieting, take your pick, our brains and muscles can survive on ketone bodies.
The ketogenic diet is extremely popular and controversial. Like you, many of its followers report less hunger and more weight loss compared to other diets. Yet experts argue its long-term effectiveness and safety.
These diets eliminate or severely restrict any type of sugar or starch including grains, fruit (natural fruit sugar, fructose), potatoes and other starchy vegetables, beans, legumes and milk (natural milk sugar, lactose).
On the plus side, ketogenic diets have been used successfully to treat epileptic seizures in children. And many people who adopt this eating plan eat more vegetables and less added sugar.
Studies over the past 15 years show that animals and humans tend to lose weight faster on ketogenic diets than with other types of diets. Their effectiveness over the long term does not seem to be any better than other weight loss plans, however.
On the down side, ketosis means that our bodies must deal with the production of acids, including acetone, that build up in our blood. This, say biochemists, disturbs the body’s natural acid-base balance.
People with diabetes are at risk of ketoacidosis — an extreme form of ketosis that is life threatening. While promoters of the keto diet say this is not a risk for healthy people, I personally do not prefer to chronically feed my brain and muscles this way.
My opinion also is that carbohydrates are not evil monsters. They are quite literally the energy from the sun transformed by plants into fuel (sugars and starches). This energy is transferred to me when I eat plant-based foods. If I severely restrict these foods, I also eliminate some pretty important nutrients and substances that reduce inflammation — a major trigger for obesity, heart disease and diabetes.
A recent study by the Agricultural Research Service, for example, found that participants who ate whole grains (instead of refined grains) lost weight while boosting beneficial bacteria in their guts that fight off inflammation and harmful gut microbes.
Any strategy that helps us avoid empty calories from excess sugars is a good step. Let’s not throw out the baby with the bathwater, however.
Barbara Quinn is a registered dietitian and certified diabetes educator affiliated with Community Hospital of the Monterey Peninsula in California. She is the author of “Quinn-Essential Nutrition” (Westbow Press, 2015). Email her at to firstname.lastname@example.org.