But if no carbs are available, our bodies start burning fat as a primary fuel source and producing ketones in the liver, which the body can turn into energy. This metabolic state, called ketosis, is what happens when someone is starving. But it's also how Harper's body works every day. His system relies on fats like butter, oil, and lard as a primary energy source instead of packing them on as in-case-of-emergency poundage.


The ketogenic diet is usually initiated in combination with the patient's existing anticonvulsant regimen, though patients may be weaned off anticonvulsants if the diet is successful. There is some evidence of synergistic benefits when the diet is combined with the vagus nerve stimulator or with the drug zonisamide, and that the diet may be less successful in children receiving phenobarbital.[3]

Many ketogenic dieters also swear by MCT oil. (MCT simply stands for medium chain triglycerides.) MCT's energy-sustaining powers can be explained as follows: When MCT oil is metabolized in the body, it behaves more like a carbohydrate than a fat. Unlike other fats, MCT oil does not go through the lymphatic system. Instead, it is transported directly to the liver where it is metabolized so it releases energy like a carbohydrate and creates lots of ketones (which can be used for fuel) in the process.
Other kinesiologists think the keto diet could have dangerous effects on athletic performance, and it's tough to know what potential side effects a long-term high-fat diet might have for a healthy person, since we don't have any solid study results yet. Low-carb diets like keto can make it easy to neglect key nutrients like magnesium, calcium, and potassium found in fresh, high-carb foods like beans, bananas, and oats.
Diarrhea can also be due to a lack of fiber in the diet, says Kizer, which can happen when someone cuts way back on carbs (like whole-grain bread and pasta) and doesn’t supplement with other fiber-rich foods, like vegetables. It can also be caused by an intolerance to dairy or artificial sweeteners—things you might be eating more of since switching to a high-fat, low-carb lifestyle.
It is possible to combine the results of several small studies to produce evidence that is stronger than that available from each study alone—a statistical method known as meta-analysis. One of four such analyses, conducted in 2006, looked at 19 studies on a total of 1,084 patients.[22] It concluded that a third achieved an excellent reduction in seizure frequency and half the patients achieved a good reduction.[3]

But if no carbs are available, our bodies start burning fat as a primary fuel source and producing ketones in the liver, which the body can turn into energy. This metabolic state, called ketosis, is what happens when someone is starving. But it's also how Harper's body works every day. His system relies on fats like butter, oil, and lard as a primary energy source instead of packing them on as in-case-of-emergency poundage.
One of the most common side effects of starting the ketogenic diet is the “keto flu.” This term describes the often unpleasant, fatigue-inducing symptoms that occur as the body adjusts from a high-carbohydrate to a low-carbohydrate diet. During the keto flu, the body’s stored glucose begins depleting, and the body starts adapting to producing and utilizing ketones as energy. (2)

How did this diet, which was first developed in the 1920s as a treatment for children with epilepsy (and has been shown to reduce seizures in patients whose epilepsy symptoms aren’t responding to other medications), become the diet du jour, and why such a discrepancy between its fandom and expert opinion? Let’s take a closer look at what “going keto” entails.
A lot of people take their macros as a “set in stone” type of thing. You shouldn’t worry about hitting the mark every single day to the dot. If you’re a few calories over some days, a few calories under on others – it’s fine. Everything will even itself out in the end. It’s all about a long term plan that can work for you, and not the other way around.

Normal dietary fat contains mostly long-chain triglycerides (LCT). Medium-chain triglycerides are more ketogenic than LCTs because they generate more ketones per unit of energy when metabolised. Their use allows for a diet with a lower proportion of fat and a greater proportion of protein and carbohydrate,[3] leading to more food choices and larger portion sizes.[4] The original MCT diet developed by Peter Huttenlocher in the 1970s derived 60% of its calories from MCT oil.[15] Consuming that quantity of MCT oil caused abdominal cramps, diarrhoea and vomiting in some children. A figure of 45% is regarded as a balance between achieving good ketosis and minimising gastrointestinal complaints. The classical and modified MCT ketogenic diets are equally effective and differences in tolerability are not statistically significant.[9] The MCT diet is less popular in the United States; MCT oil is more expensive than other dietary fats and is not covered by insurance companies.[3]
Make things yourself. While it’s extremely convenient to buy most things pre-made or pre-cooked, it always adds to the price per pound on items. Try prepping veggies ahead of time instead of buying pre-cut ones. Try making your stew meat from a chuck roast. Or, simply try to make your mayo and salad dressings at home. The simplest of things can work to cut down on your overall grocery shopping.
What's more, it's especially important to make sure your diet is well-planned when you're eating keto-style, because the foods you can choose from are limited. In addition to checking in with a dietitian if you're able, Stefanski recommends that you "talk to your doctor and make sure she or he is aware that you'll be starting a diet that completely changes how your body metabolizes energy." You might also want to check your most recent bloodwork levels for things such as cholesterol, vitamin D, and other indicators of health because these can change while on keto. That's because for some people, a prolonged keto diet can result in certain nutritional deficiencies or even high cholesterol. But most experts will tell you that the ketogenic diet is not a permanent lifestyle change (as could be the case for something like the 80/20 approach to eating or a Mediterranean eating style).
But it's not just the flavor factor. This high-fat, moderate-protein, and very low-carb diet (which is usually broken down as 70 to 75 percent fat, 20 to 25 percent protein, and 5 to 10 percent carbs) can actually leave you feeling physically ill, especially in the beginning. After a week or two on the diet you will enter full ketosis. But until you get there, symptoms like extreme fatigue (the feeling like you can't get out of bed) and the keto "flu" may occur. The keto "flu" is the time where your body is adapting to using ketones as energy, which can leave you feeling nauseated, with headaches, and a foggy head.
This can be tough for folks who need a "cheat" day, but it can also take a mental toll on the dieter. In a usual diet plan when you go off of it for a day or two, you just get right back in the saddle and start again. With keto it's more than that: You need to start from scratch to get yourself back into ketosis, which can take a few days or weeks. This can really make you feel bad about yourself and take a psychological toll on your well-being and self-worth. (Related: Why You Should Give Up Restrictive Dieting Once and for All)

Selecting the right food will be easier as you become accustomed to the Keto approach. Instead of lean meats, you’ll focus on skin-on poultry, fattier parts like chicken thighs, rib-eye steaks, grass-fed ground beef, fattier fish like salmon, beef brisket or pork shoulder, and bacon. Leafy greens such as spinach, kale and lettuce, along with broccoli, cauliflower and cucumbers, make healthy vegetable choices (but you’ll avoid starchy root foods like carrots, potatoes, turnips and parsnips). You can work in less-familiar veggies such as kohlrabi or daikon.
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