Eating all the fat you want sounds like a delicious way to lose weight—but lets see how long you can hack it.
I’ve been a dietitian for almost 20 years. Few things surprise me. But I had to ask: “Why?”
She told me that her husband had heard about a new diet on TV, the keto diet, and they decided to try it. Six months and countless packages of bacon later, her husband had lost 20 pounds and said he felt more energetic.
I’m beginning to hear more and more people lecture me about the benefits of the ketogenic diet. “Keto burns fat fast! It turbo-charges your energy! It fights disease! You can eat all the bacon you want!” But as is so often the case with diets, underneath all the initial excitement, there’s a gut check. Here’s everything you should know about the ketogenic diet and whether or not you should try it for yourself.
Ketogenesis has existed as long as humans have. If you eat a very low amount of carbonhydrates, you starve your brain of glucose, its main fuel source. Your body still needs fuel to function, so your brain signals it to tap its reserve of ketones. It’s like a hybrid car that runs out of gas and reverts to pure electricity.
Okay, but what are ketones? They’re compounds created by your liver from your fat stores when blood insulin is low. “Your liver produces ketones all the time, but the rate depends on carbohydrate and protein intake,” says Jeff Volek, Ph.D., R.D., a professor of human sciences at Ohio State University. Eat a normal amount of carbs and protein, and ketogenesis idles. Cut carbs and protein back, and you push to half throttle. This takes about three days to induce.
A ketogenic diet requires that fat comprise 60 to 80 percent of your total calories. Protein makes up 10 to 15 percent, and less than 10 percent comes from carbs. Yes, less than 10 percent. That’s the equivalent of about half a medium bagel.
A sample day on a ketogenic diet:
BREAKFAST: 4 eggs, 1/2 avocado, 1 to 2 Tbsp olive oil
LUNCH: 4 oz baked salmon with 1 Tbsp olive oil, 1/2 bunch asparagus with 1 to 2 Tbsp butter
DINNER: Rib-eye steak, 2 cups spinach with coconut oil, 2 oz macadamia nuts
If this sounds like Atkins, it’s close, but “ketogenic diets tend to be more severe in carb restriction and have a more moderate protein restriction,” says Spencer Nadolsky, D.O., author of The Fat Loss Prescription.
Some theories even suggest that if you rely less on carbs, your body will burn more fat as fuel, which may boost physical and mental performance, regulate appetite, lower insulin, and enhance immunity.
Most men consume nearly half of their calories from carbs, according to the Centers for Disease Control and Prevention. So here’s the challenge: Can you sustain ketosis long enough to reap the purported health benefits?
This may sound like a copout, but the best diet is the one you stick with. For Volek, who’s been following an ultra-low-carb diet for two decades, it works. But for you?
Unfortunately, there’s no long-term data on ketogenic diets versus other diets. The closest attempt came out in 2007. A project nicknamed “The A to Z Weight Loss Study” compared the Atkins, Zone, LEARN, and Ornish diets for long-term weight loss. The female subjects assigned to the low-carb diet of 20 percent carbs were eating close to 35 percent by the end of 12 months—a far cry from the 10 percent or less required for ketosis.
Studies have shown that people do lose weight on a ketogenic diet, but there’s a catch. In a 2015 Italian study, those on a ketosis diet lost 26 pounds in three months. About half of the participants stayed on the diet for a year but lost little additional weight in the next nine months. People in a 2014 Spanish study who followed a very-low-calorie ketogenic diet lost an average of 44 pounds in a year—but a third of them dropped out.
Though you can eat bacon on a ketogenic diet, the rest of the spectrum is limited. Starchy vegetables like potatoes, corn, and squash are too high in carbs. Same with most fruits. Milk, beans, rice, pasta, bread: nope.
Some experts label the diet impractical. “Extreme diets such as the ketogenic diet have no therapeutic or practical use for people without neurodegenerative disorders such as epilepsy,” says Alan Aragon, M.S., a Men's Health nutrition advisor.
Can’t you take ketone supplements? No. While it is possible to elevate ketones by taking them, “without the low-carb stimulus, there is no net increase in ketone production, no decrease in insulin, and no net increase in fat oxidation,” says Volek. Don’t trust trainers or “body hackers” who say you can induce ketosis quickly without changing your diet.
Is keto right for you? If you’re an elite endurance athlete who does well with structured diets and wants an edge, maybe. If you’re just a guy who wants to drop 10 pounds and has had trouble with yo-yo dieting, probably not. But you can take three lessons from the diet:
Instead of thinking about the overall number of carbs you’re eating, assess what those carbs are providing to you. Do the majority of your carbs come from fruit, with its payload of fiber and disease-fighting antioxidants? Fantastic. Or are you consuming them in the form of added sugars (cookies, candy, soda) or refined flour? If you are, you know what to do.
The ketogenic diet may seem like the Jekyll to the Hyde-like low-fat craze of the 1990s. The bulk of current research finds that the middle ground between the two extremes is more beneficial for overall health. Make it easy for yourself: Eat at least two servings a week of fatty fish (salmon, sardines, mackerel) and cook with a variety of quality fats (olive oil, canola oil, avocado oil) throughout the week.
Grill Slammin' Salmon:
Leafy vegetables are loaded with nutrients. Keto fans love them; so should you. There’s kale, spinach, bok choy, Swiss chard, collards, watercress, mizuna, and arugula. Dig in.
Oh, and you might be wondering—how’d things turn out with the bacon beaus? Their experiment worked until life changed. They had a kid. They made a big move. They stopped the diet. “It was too hard to maintain,” she told me. Proof that all the bacon you can handle even grows boring after a while.