No doubt you've already heard about the ketogenic diet, also known as Keto. Whole Pinterest boards and Instagram accounts are dedicated to the trend, and it has some pretty famous followers, including Halle Berry and Kourtney Kardashian.
Before you give it a go, you'll want to know what it involves, how it works and, most importantly, what nutritionists and doctors think about the keto diet.
So what IS Keto, anyway?
The Keto diet is a very low- or no-carb food plan that forces the body into a state of ketosis, which is when your body burns fat for energy instead of carbohydrates. Many Keto diets limit the amount of food you should eat, like any other weightloss plan, but with Keto the type of food you can eat is just as important as the quantity.
So what can you eat on the Keto diet? Get ready to feast on fish, other seafood, low-carb vegetables (forget potatoes or carrots), cheese, meat, poultry, eggs, plain yoghurt, and of course fats. The foods you'll be forgoing include fruits, grains (including bread and pasta), legumes and anything with added sugar.
On a standard ketogenic diet, your calories should be made up of 75 percent fat, 20 percent protein, and 5 percent carbohydrate. This is unlike most typical diets, and can be a hard adjustment for many people.
The good news: Keto can be an effective tool for losing weight when monitored by a doctor.
Though the Keto diet can be hard to stick to, it has been shown to result in weightloss — at least in the short term. Research from 2014 published by the International Journal of Environmental Research and Public Health shows that "the ketogenic diet can be a useful tool to treat obesity in the hands of the physician". The key here is that a doctor should be monitoring the process to avoid potential problems.
Dr Nancy Rahnama, a board-certified internist specialising in nutritional health from Los Angeles, told HuffPost that "the Keto diet is a very successful way for rapid weightloss, as long as it is done safely". Which brings us to the bad news.
The bad news: Keto flu.
As with any health trend, especially one that can seem restrictive, there have been some specific concerns raised by the medical community that the Keto diet might not be a safe or realistic long-term eating plan.
Dr Amnon Beniaminovitz, a board-certified cardiologist from Manhattan Cardiology in New York City, told HuffPost that some people can feel unwell when they first start the Keto diet, a phenomenon known as the "Keto flu."
"It is common for people starting the diet to experience symptoms such as headaches and fatigue, dizziness, light nausea, difficulty focusing (brain fog), lack of motivation and irritability," Beniaminovitz said.
These are the same sort of symptoms people experience when they wean themselves off caffeine or soft drinks, leading some to suggest the diet is a period of detox.
Kristin Kirkpatrick, a registered dietician and Lose It! nutrition expert from Denver, has tried the Keto plan herself, so that she knows firsthand what some of her clients are experiencing. She told HuffPost the "Keto flu" is real, but you need to stick with the diet to see results.
"The beginning of the Keto plan can be overwhelming," Kirkpatrick said. "Hangry doesn't even begin to describe it. But once your body gets used to a low glucose supply, there's almost a sense of euphoria."
We still lack long-term studies on Keto.
Ginger Hultin, a Seattle-based registered dietitian, nutritionist and Arivale coach, is concerned that despite results suggesting successful short-term weightloss, the Keto philosophy lacks scientific research on the long-term effects.
"There is a possibility of kidney damage, nutritional deficiencies, and side effects including constipation, dehydration, fatigue and nausea with this diet. Individuals and their healthcare professionals should weigh the advantages and disadvantages," Hultin said.
Keto's high fat intake can impact heart health.
Keto diets encourage people to eat foods they have traditionally been told to avoid, including lots of meat and saturated fat.
"In general, Keto diets involve a high intake of animal products, which contain a lot of saturated fat and animal protein," Dr Nicole Harkin, a board-certified cardiologist, lipidologist and clinical assistant professor at New York University, told HuffPost. "As a result, LDL cholesterol tends to increase on these diets, a consistent risk factor for the development of cardiovascular disease."
There are potential benefits beyond just weightloss.
There is some evidence that a Keto diet can be effective for patients with epilepsy. This treatment is offered at Stony Brook Medicine, where Dr Josephine Connolly-Schoonen is chief of the nutrition division and an expert in the nutritional management of obesity and chronic illnesses. "The ketogenic diet is especially effective for decreasing seizure activity among people with epilepsy," she told HuffPost.
Small studies have also shown promising results for women diagnosed with polycystic ovarian syndrome who follow a Keto diet.
Blood-sugar levels have also been shown to stabilise on keto diets, which is particularly important to those with diabetes.
There have even been some studies showing that very low-carbohydrate diets can be used effectively in the prevention and treatment of various cancers, an area that certainly requires more research.
The Keto trend doesn't seem to be going away anytime soon. And when followed consistently for the short term with appropriate monitoring, it can lead to weightloss. Further research is required to highlight potential treatments for disease and any possible health problems associated with the Keto lifestyle. Always refer to your doctor before beginning a new diet or lifestyle plan.