That’s why many health experts are concerned about people on the keto diet, especially those who try it without the guidance of a doctor or nutritionist. Doctors say that high-fat diets like this one may raise cholesterol levels, and some studies suggest that they increase the risk of diabetes. Some have even called it a “cardiologist’s nightmare.”
Have to work late tonight and need dinner—in a hurry? Not to worry. If you find fast food is your only option, pull up the restaurant's nutrition facts online before you go; you can make an informed decision ahead of time about what to order. "Nearly every quick-service restaurant has a relatively healthful option or two," says Newgent. We're thinking salads, chili, or grilled chicken. Some low-cal, healthy, on-the-run dishes: the vegetarian burrito bowl at Chipotle, the Bangkok curry at Noodles and Company, and the tomato basil bisque at Au Bon Pain.
On the ketogenic diet, carbohydrates are restricted and so cannot provide for all the metabolic needs of the body. Instead, fatty acids are used as the major source of fuel. These are used through fatty-acid oxidation in the cell's mitochondria (the energy-producing parts of the cell). Humans can convert some amino acids into glucose by a process called gluconeogenesis, but cannot do this by using fatty acids.[57] Since amino acids are needed to make proteins, which are essential for growth and repair of body tissues, these cannot be used only to produce glucose. This could pose a problem for the brain, since it is normally fuelled solely by glucose, and most fatty acids do not cross the blood–brain barrier. However, the liver can use long-chain fatty acids to synthesise the three ketone bodies β-hydroxybutyrate, acetoacetate and acetone. These ketone bodies enter the brain and partially substitute for blood glucose as a source of energy.[56]

That’s why many health experts are concerned about people on the keto diet, especially those who try it without the guidance of a doctor or nutritionist. Doctors say that high-fat diets like this one may raise cholesterol levels, and some studies suggest that they increase the risk of diabetes. Some have even called it a “cardiologist’s nightmare.”
Whether or not you need specialty bars and other packaged goods formulated with probiotics is another matter. “Science has not shown that probiotics improve general health,” says Dr. Shira Doron, infectious diseases physician and associate hospital epidemiologist at Tufts Medical Center. “Certain diseases and conditions have been studied, with varying results, some of which suggest that probiotics can mitigate symptoms. If you’re taking a probiotic for a specific condition, it is critically important that you use the same strain, formulation and dose that were shown to be effective in clinical trials; otherwise you cannot assume you will experience the same positive effect,” she explains.
After stepping on the scale, he considered weight-loss surgery. Like anyone opting for gastric bypass surgery, he had to lose some weight prior to the procedure and started following an eating plan. He added foods high in lean protein, low in carbs and rich and fruits and vegetables. The first month, he dropped 25 pounds. The second month, he shed 30 pounds. By June he had lost 100 pounds and his doctor was shocked.
Research shows that exercise alone won’t help you lose weight, and contrary to popular opinion, it’s not the right message for the worldwide obesity epidemic. A recent study reveals why, suggesting that your body adjusts to higher activity levels, so while you may burn extra calories initially, eventually that rate will plateau. And there is some disheartening research, indicating that solely using exercise as a weight loss method can actually lead to weight gain. “Clients always say, ‘I’m doing all of this activity, but I just can’t lose the weight,’” confirms Mangieri. “I even have athletes who are training for 5Ks, 10Ks, and half marathons, and still gaining weight.”
On the other hand, nutritionists like Turoff aren’t thrilled with the orange juice choice. “Orange juice is going to be high in sugar, so I wouldn’t recommend it for the average person — instead, I suggest having a whole orange,” says Turoff. By doing so, she says, you get the fiber from the whole fruit, which helps keep your blood sugar from spiking, like it does with juice.
Your body does not store protein the way that it stores carbohydrates and fats. This means that your diet is the critical source for this essential nutrient. More is not better, so there is no need to go above the recommendations. In fact, research has shown that very high protein diets can lead to increased calcium loss and weakened bones. Be sure to add a protein source to each meal to curb your hunger and keep you healthy.
The keto diet isn’t new, and it’s been around for nearly a century. It was originally developed to treat people with epilepsy. In the 1920s, researchers found that raised levels of ketones in the blood led to fewer epileptic seizures in patients. The keto diet is still used today to treat children with epilepsy who don’t respond well to anti-epileptic drugs.[2]
The ketogenic diet reduces seizure frequency by more than 50% in half of the patients who try it and by more than 90% in a third of patients.[18] Three-quarters of children who respond do so within two weeks, though experts recommend a trial of at least three months before assuming it has been ineffective.[9] Children with refractory epilepsy are more likely to benefit from the ketogenic diet than from trying another anticonvulsant drug.[1] Some evidence indicates that adolescents and adults may also benefit from the diet.[9]

Alison Moodie is a health reporter based in Los Angeles. She has written for numerous outlets including Newsweek, Agence France-Presse, The Daily Mail and HuffPost. For years she covered sustainable business for The Guardian. She holds a master’s degree from Columbia University’s Graduate School of Journalism, where she majored in TV news. When she's not working she's doting on her two kids and whipping up Bulletproof-inspired dishes in her kitchen.
The keto diet changes the way your body converts food into energy. Eating a lot of fat and very few carbs puts you in ketosis, a metabolic state where your body burns fat instead of carbs for fuel. When your body is unable to get glucose from carbs, your liver converts fatty acids from your diet into ketones, an alternative source of energy. Burning ketones in place of glucose reduces inflammation and spurs weight loss.[1]
Similar to the CICO diet, the Body Reset has gained popularity via social media, and there isn’t any definitive research that suggests the approach is safe and effective. Celebrity trainer Harley Pasternak created the plan, which is essentially a three-phase liquid diet comprised of smoothies and moderate exercise. While U.S. News notes you may lose weight on the diet, it may be tough to stick with, and isn’t safe for people with diabetes and heart disease. (38)

Besides the well-known medical problems individuals can develop as a result of weight gain (high blood pressure, diabetes, cancer, stroke, and heart disease), extra weight puts additional stress on joints and bones. For example, the corticosteroid prednisone causes weight gain to some degree in nearly all patients who take the medication and can lead to redistribution of body fat to places like the face, back of the neck, and abdomen.
“As a rule of thumb, weight loss is generally 75 percent diet and 25 percent exercise. An analysis of more than 700 weight loss studies found that people see the biggest short-term results when they eat smart. On average, people who dieted without exercising for 15 weeks lost 23 pounds; the exercisers lost only six over about 21 weeks. It’s much easier to cut calories than to burn them off. For example, if you eat a fast-food steak quesadilla, which can pack 500-plus calories, you need to run more than four miles to ‘undo’ it!
Note: Are you a vegetarian or vegan and want to go on a ketogenic diet? It’s still possible! Just keep in mind that the dietary restrictions can sometimes be a little bit intense. Make sure to plan ahead and prepare to aid your success. To help out, we’ve published articles (with 7 day meal plans included) for both the vegetarian ketogenic diet and the vegan ketogenic diet.
^ Freeman JM, Vining EP, Pillas DJ, Pyzik PL, Casey JC, Kelly LM. The efficacy of the ketogenic diet—1998: a prospective evaluation of intervention in 150 children. Pediatrics. 1998 Dec;102(6):1358–63. doi:10.1542/peds.102.6.1358. PMID 9832569. https://web.archive.org/web/20040629224858/http://www.hopkinsmedicine.org/press/1998/DECEMBER/981207.HTM Lay summary]—JHMI Office of Communications and Public Affairs. Updated 7 December 1998. Cited 6 March 2008.
This high-fat, adequate-protein, low-carb fad diet sends the body into a state of ketosis, in which the body uses stored fat for energy. Research published in Clinical Cardiology suggests the ketogenic, or “keto,” diet can be an effective weight loss method, but to be successful, you must follow the plan consistently with no cheat days — otherwise, you’re just eating a high-fat diet that may be high in unhealthy fats for no reason. (1) (A pro tip? If you're planning on doing the diet, consider perusing this complete keto food list and reading up on the healthiest fats for keto diet followers.)
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