- Getting into ketosis means changing how your body gets energy.
- Ketosis means you're burning fat for energy instead of carbs so cutting carbs is key.
- You can also get into ketosis by exercising more, fasting, and limiting protein.
Ketosis is the hallmark of rapid weight loss in popular diets like the ketogenic diet and intermittent fasting.
There are several ways you can enter ketosis. The bottom line is just that you have to deplete your glucose reserves.
Glucose is your body's main source of energy and it typically comes from the carbs you eat.
Here's how cutting carbs, exercising, fasting, and other tips can help you reach ketosis. But first an important note about the keto diet:
What to know about keto
The ketogenic diet was initially developed to treat epilepsy in children, but it has become a popular approach to weight loss.
"While there are many claims of drastic weight loss, this diet was not intended for weight management purposes," says Kailey Proctor, RDN, a board certified oncology dietitian at the Leonard Cancer Institute at Providence Mission Hospital.
Because of that, people should not aim to maintain ketosis long term. Especially since you usually have to drastically reduce whole grains, vegetables, and fruits — and their healthy fiber, vitamins, and minerals — to stay under 50 grams of carbs per day.
"It is extremely difficult to meet vegetable and fiber requirements following a keto diet," says Proctor.
If you are on a ketogenic diet for medical reasons, it's important to work with a doctor or dietitian.
With that, here are five thing you can do to help you reach ketosis and some tips on how to know when you reached your goal.
1. Cut carbs
Keto diets typically limit carbohydrate intake to less than 50 grams per day, says Proctor.
The reason being that with limited carbs, your body has nothing to convert to glucose. And without glucose, the body's forced to burn fat for energy instead, via a process called ketosis.
After limiting carbs, it can take up to a week for the body to use up any remaining glucose stores and reach ketosis. But keep in mind, it's important to remain in a carb deficit.
"As soon as more than 50 grams of carbohydrates are consumed, you are no longer in ketosis and must go through the process of drastically limiting carbohydrates again," says Proctor.
Proctor along with other professionals recommend upping fruit and vegetable intake, rather than decreasing it, even if that interferes with ketosis.
2. Eat more healthy unsaturated fats
Eating a diet rich in fat while also limiting carbs prompts your body to burn fat, rather than glucose, for fuel. That's the basis of ketosis.
People following a ketogenic diet get 75% of their calories from fats, which ideally should come from avocado, nuts, olive oils, and other unsaturated, or healthy, fats.
For comparison, the Dietary Guidelines for Americans recommends that people older than 14 only get 20% to 35% of their caloric intake from fats, including unsaturated fats.
While consuming more fats can promote ketosis, it's important to make sure you're limiting saturated fat and mainly consuming unsaturated fats.
"A diet high in saturated fat has been shown to increase the risk of heart disease and heart attacks as these fats are more likely to clog our arteries," says Proctor.
3. Fast intermittently
The body enters ketosis when it doesn't have glucose to burn, including after fasting for about 12 hours. However, fasting alone isn't enough to promote ketosis for most people.
"The intake of carbohydrates at the end of their fasting window would quickly eliminate the need to rely on fat for fuel," says Cara Harbstreet, RD, founder of Street Smart Nutrition.
Because of limited benefits and possible negative outcomes, Harbstreet doesn't recommend fasting outside of established religious or cultural purposes.
"The planned and intentional restriction of food is a known dieting behavior that can be moderately to highly disordered for many people," she says.
4. Eat less protein
On a keto diet designed to treat epilepsy, only 10% to 15% of calories come from proteins, Harbstreet says. Eating more than that can bump your body out of ketosis.
By comparison, keto diets designed for weight loss often recommend 20% to 30% of calorie intake be from protein, Harbstreet says, but this can make it difficult to maintain ketosis.
"When eaten in excess, protein can be converted to glucose, which can make it harder or impossible to achieve and maintain ketosis," Harbstreet says.
The Dietary Guidelines suggest that adults get 10% to 35% of their daily calories from protein.
5. Exercise more
During exercise, the body quickly uses up its glucose reserves. Therefore, if you're going longer than a couple of hours, the body switches over to burning fat for fuel via ketosis because there's no glucose left.
That's why prolonged exercise can speed up the process of getting into ketosis, Harbstreet says.
Of course, everyone can benefit from regular exercise. Aim to meet the current recommendations of 150 minutes a week of moderate intensity exercise, or 75 minutes per week of high intensity exercise.
Signs you're in ketosis
Once your body is in ketosis, you might notice physical changes including symptoms of the keto flu, like nausea, irritability, and confusion.
You may also notice a fruity or acetone scent on your breath, which indicates increased ketones — the byproduct of ketosis — in your bloodstream.
There are also urine strips that can measure the amount of ketones in your pee to identify ketosis, but these products are not particularly reliable, Proctor says.
Measuring ketone levels in your blood, on the other hand, is accurate, but blood ketone meters are expensive, she says.
So, your best bet is looking for physical symptoms of ketosis and making sure you're limiting your carb and protein intake.
Insider's takeaway
There's a lot of buzz about the keto diet, but a true keto diet should only be done under the supervision of a medical professional, says Harbstreet.
"I can't endorse or recommend that anyone strives to maintain ketosis or a keto diet indefinitely," she says.
It's difficult to get adequate nutrition on the keto diet, and there are possible cardiovascular side effects, Harbstreet says, adding that people should focus on sustainable healthy eating rather than trying to enter ketosis through strict dieting regimens.
"The heightened interest in the keto diet is not unlike past diet fads, in which the initial development of the diet is perhaps rooted in some legitimate nutrition science, but has evolved into something nearly unrecognizable," she says.
