15 Keto Diet Questions Answered: Weight Loss, Safety, and More
Diet & NutritionKetogenic Diet

Answers to 15 Burning Questions About the Keto Diet

Answers to 15 Burning Questions About the Keto Diet
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Updated on September 20, 2026
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When it seems like everyone has tried the ketogenic diet, you may want to know if it’ll work for you. The keto diet is a high-fat, moderate-protein, very low-carb eating plan. But while people say that you can eat all the butter and bacon you want and still lose weight, is it really true — or healthy, for that matter?

Data on the keto diet's short-term benefits for weight loss and cholesterol, blood pressure, and blood sugar control is promising, although longer-term research is necessary to champion it over other diets for weight management.

 Here are your top keto questions, including its effects, safety, and how it works, answered by experts and research.

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5 Myths About the Keto Diet

1. Is the Keto Diet Healthy?

The keto diet originated as a therapeutic diet that physicians prescribed to control seizures in people who have certain types of epilepsy.

 For those people, a keto diet may support their health (and even so, it’s vital to use a keto diet for epilepsy management only with regular medical monitoring).

 But a keto diet certainly isn’t necessary for health in most people.
Today, the diet has become trendy, and many people use it for weight management. However, some people on the keto diet end up eating high levels of saturated fat, which may pose a risk for long-term heart health.

 And in the short term, severely low-carb diets may come with unpleasant side effects, like constipation and headaches.

Given that keto is restrictive enough to eliminate most fruit and dairy, whole grains, many vegetables, and legumes, you may also fall short in terms of certain nutrients, like fiber, vitamins A and E, calcium, magnesium, potassium, iron, several B vitamins, and vital plant compounds that help your body protect you against illness.

2. Is the Keto Diet Safe to Follow?

The keto diet is so called because it triggers ketosis, the natural metabolic state in which your body burns fat instead of its usual fuel source, glucose, which is a kind of sugar. Even though following an extremely high-fat diet can feel like a radical way to eat, “the research looking at ketosis via diet has not shown any real negative consequences when done in the short term,” says Scott Keatley, RDN, of Keatley Medical Nutrition Today in New York City.

“But there have been few long-term studies,” says Kendra Whitmire, a clinical nurse specialist who practices functional and therapeutic nutrition in Laguna Beach, California. It’s difficult to definitively say that it’s safe, and it largely depends on the foods you’re eating on the keto diet. For instance, one review suggests that foods high in polyunsaturated fats, such as salmon and olive oil, are better for chronic disease prevention than foods high in saturated fats, such as bacon and butter.

“That said, following the keto diet properly, and particularly with help from a medical professional, should reduce negative health effects,” says Whitmire.

3. Is Ketosis Bad for You?

Beyond the keto flu (a series of short-term side effects as your body gets used to ketosis),

 “many studies have shown that entering ketosis via diet does not have any real negative consequences in the short term,” says Keatley. Long-term studies are needed to truly assess the impact of ketosis, he adds.

Bottom line: Putting your body into ketosis for a limited time is likely not harmful for most healthy people.

4. How Many Carbs Do You Actually Eat on a Keto Diet?

“A keto diet is generally made up of 70 to 75 percent fat, 20 to 25 percent protein, and 5 to 10 percent carbohydrates,” says Jill Gulotta, RDN, who is in private practice in White Plains, New York.

The exact number of grams (g) of carbohydrates will vary from person to person, but it is generally around 20 to 50 g per day. Many people on a keto diet count net carbs, which is total carbs minus fiber. Some people on keto don’t count fiber in the carbohydrate total, as the body doesn’t digest it, although there’s debate among those who pursue ketosis whether fiber should be included in the carb count.

Either way, that number of carbs is very low and requires careful planning. The recommended daily allowance for carbs is 130 g daily, with 45 to 65 percent of your daily calorie intake coming from carbs.

 Eating a little fruit, starchy vegetables, sugary foods, or whole grains can easily mean you drop out of ketosis.

5. Can You Drink Alcohol on the Keto Diet?

Yes. “Even though there are often carbs in alcohol, you can still drink it in limited amounts,” says Keatley. However, on days when you consume alcohol, you may have to adjust your carbs from other sources, depending on the kind of alcohol you have. That might mean making tough decisions, like having a drink but skipping a small amount of fruit or Greek yogurt.

Spirits (enjoyed straight, without mixers) tend to be the most keto-friendly alcohol, followed by wine. You may want to halve your usual serving, says Keatley. Beer and wine can eat up a lot of your carbs, and they don’t give back in terms of vitamins and minerals. “It’s a waste of your carbs,” he says.

Here are the carbs included in four main alcoholic drinks per servings in fluid ounces (fl oz), according to the U.S. Department of Agriculture (USDA). These can vary from manufacturer to manufacturer, so always check the label:

  • Spirits (1.5 Fl Oz) 0 g carbs in one serving, including gin, rum, vodka, and whiskey

  • Red Wine (5 Fl Oz) 4 g carbs in one serving

  • White Wine (5 Fl Oz) 4 g carbs in one serving

  • Light Beer (12 Fl Oz) 6 g carbs (stick to half of a beer if this is your choice)

If you’re trying the keto diet to support weight management, it’s worth noting that regardless of carb count, drinking alcohol is a source of extra calories and can make losing weight more difficult. So if you’re looking to drink alcohol while on keto, do so in moderation, stay active, and drink plenty of water before, during, and after nights when you’ve been consuming alcohol.

6. How Much Weight Can You Lose on the Keto Diet?

There’s no doubt that a ketogenic diet may help spur weight loss, at least initially, and anecdotal reports of drastic transformations are easy to find. “I have clients who have lost a significant amount of weight on a keto diet, but they were obese when starting and had quite a bit of fat to lose. These individuals can have fairly drastic body transformations,” says Keatley.

Very low-calorie keto diets have produced rapid short-term weight loss under clinical supervision. A meta-analysis pooled data from 15 clinical trials evaluating adults with obesity following a medically supervised keto diet that allowed fewer than 800 calories per day. In the initial short-term phase of around a month, participants lost an average of 22 pounds (lbs) and experienced significantly greater weight loss, fat loss, and waist size reduction than those on non-keto, low-calorie diets lasting the same amount of time.

However, the diet followed included just 600 to 800 daily calories, which is well below what most health professionals recommend without close medical supervision.

While a ketogenic diet can appear to jump-start rapid results, longer-term studies show that its weight loss advantage over diets that don’t restrict carbs eventually narrows because it can be harder to follow for a long time.

A meta-analysis included data from 23 clinical trials comparing adults with type 2 diabetes on low-carbohydrate or keto diets to those on more standard diets. At six months, low-carb dieters had lost an extra 10 lbs on average, compared with the control group. However, by 12 months, that advantage had shrunk to less than 4 lbs, as fewer people stuck to the diet.

The bottom line is that many diets, including keto, may lead to similar weight loss in the long run. “With that news, know that there may be a better option out there for you,” says Keatley.

7. What Fruit Can I Eat on the Ketogenic Diet?

Fruit is generally not a mainstay of the keto diet. With so much natural sugar, fruit generally has too many carbs to be included.

But you can have small amounts of lower-carb fruits, like berries, says Whitmire. And if you’re really getting technical, avocados and coconuts, two higher-fat foods, are in fact fruits. Per the USDA net carb counts (total carbs minus fiber), here are the fruits that can work on a keto eating plan:

  • Raspberries 3 g net carbs per ½ cup

  • Strawberries 5 g net carbs per ½ cup

  • Blueberries 9 g net carbs per ½ cup

  • Blackberries 3 g net carbs per ½ cup

  • Raw Coconut 2.5 g net carbs per ½ cup

  • Avocado 1.5 g net carbs per ½ cup

8. Can I Eat Snacks Like Popcorn, Oatmeal, and Yogurt on Keto?

High-carb foods like popcorn and oatmeal probably won’t fit in the keto diet. A cup of air-popped popcorn contains 5 g of net carbs, which may be a quarter of your carb allotment for the entire day.

And that’s not a large serving, providing just 30 calories and no fat, so it’s unlikely to be filling. Oatmeal likely doesn’t fit with a keto diet either. About a quarter cup of plain dried oats (about half a cup cooked) has 12 g of net carbohydrates for 77 calories and just 1 g of fat.

 As for yogurt, it depends on what type you choose and whether it’s keto compliant. A container with 6 oz of plain 5 percent milk fat Greek yogurt from Fage, for instance, contains 5 g of carbohydrates.

 Remember to choose plain versions, as flavored ones will add more sugar (and therefore more carbs).

Whitmire recommends nonstarchy veggies, such as broccoli and cucumbers, and small amounts of low-carb fruits like berries, as better keto-compliant snacks. She also suggests the following:

  • Nuts (1 oz of almonds has 3 g net carbs)

  • Seeds (1 oz has 3.23 g of net carbs)

  • Beef jerky (1 oz provides 2.61 g net carbs)

   Poll

What’s the biggest challenge you face on the keto diet?

9. Should I Be Concerned About the Keto Flu?

If you’re interested in the keto diet, you have probably read about the keto flu, one not-so-fun side effect.

“The keto flu is definitely real,” says Keatley. “Your body functions really well on carbohydrates — that’s what it was designed for. When it switches to fat burning, it becomes less efficient at making energy,” he says.

On keto, you have less energy available, and you may feel sick and sluggish, as if you have the flu. It’s not a fever or a flu virus, though – the side effects are simply similar to those of the flu, often including fatigue and headache. As your body naturally adjusts to this new way of drawing energy, you will come out of it.

 This may take a couple of weeks, says Keatley.

10. Will the Keto Diet Give Me Kidney Stones?

“Consuming high levels of red meat and not drinking a lot of water may make stones more likely,” says Whitmire.

She adds that on a keto diet, you need to stay hydrated and replenish electrolytes (minerals like sodium, potassium, magnesium, and calcium). “If not, this can increase your risk of side effects like stones,” she says.

Research offers a small glimpse into how likely kidney stones are. A systematic review and meta-analysis found that people who follow the keto diet have a slightly elevated risk of developing kidney stones.

The researchers found that the overall incidence of kidney stones in people on the keto diet is 5.9 percent, compared with an incidence of 0.3 percent in males and 0.25 percent in females among the general population.

This doesn’t mean that you’ll definitely get kidney stones on keto. But if you have risk factors for kidney stones, like a family or personal history of stones, talk to your doctor about any precautions you should take when on the keto diet.

11. How Might the Keto Diet Affect My Period?

You may notice changes in your menstrual cycle on keto. “Studies on younger women who eat severely low-carb diets for an extended period of time have found that they end up with irregular periods or missed periods,” says Whitmire.

 “Women may need more carbs on a keto diet compared with men, especially if a woman is noticing a change in her cycle.”

At the other end of the spectrum, limited evidence has found that for women with polyendocrine metabolic ovarian syndrome (PMOS), a ketogenic diet may improve their hormonal balance.

A systematic review that evaluated data from a small group of women with PMOS who followed keto diets saw reduced free testosterone and fasting insulin levels, and balanced levels of luteinizing and follicle-stimulating hormones.

 And another study from a single medical center found that a 45-day keto diet followed by a 45-day gradual reintroduction of carbs helped regulate menstrual cycles.

Again, talk to your doctor before starting, especially if you’re using the diet as part of your treatment.

12. How Long Do You Need to Stay on the Keto Diet to Lose Weight?

Anecdotally, many people report losing weight quickly on a keto diet, says Keatley. A study of pooled data found that dieters with obesity lost an average of 16.5 lbs after one month, 33.2 lbs over two months, and 36.9 lbs when checking in between four and six months following a very low-calorie keto diet.

 As with many other studies, this looked at combining ketosis with a very low calorie intake that would normally not be healthy to maintain.

Keatley suggests to clients that they spend no more than 12 weeks in ketosis because of the uncertainties of following it long term and the risk of developing nutritional deficiencies.

When people stop a keto diet and begin to incorporate more carbs into their day, they tend to regain some weight during the adjustment period, he says. They also stand to regain all the weight they lost if they return to their pre-keto eating patterns after feeling deprived while on the plan.

13. How Will the Keto Diet Affect Your Cholesterol Levels?

The interesting thing about a keto diet is that it often leads to weight loss, something that by itself can improve blood lipid levels. At the same time, you may be consuming more saturated fat than ever, in the form of butter, bacon, cream, and coconut oil.

Eating excess saturated fat can raise cholesterol and increase a person’s risk of heart disease.

 However, other research has found that although the keto diet increases saturated fat intake a moderate amount, it’s not enough to significantly increase a person’s risk of heart problems unless they have a genetic condition that means they’re prone to high cholesterol levels.

A small study of patients with obesity who were on a keto diet found that after 20 weeks, total cholesterol and HDL (“good”) cholesterol levels increased despite body fat decreasing by 4.41 percent and blood pressure and blood sugar coming down.

Research has shown that some types of ketone bodies can protect the heart by improving blood vessel function, boosting nitric oxide (a compound that keeps arteries relaxed), and lowering inflammation.

However, the keto diet carries some heart health risks. Sticking to a keto diet long term can cause overall cholesterol imbalances, potential nutrient deficiencies, and increased strain on the kidneys. Individual responses vary and can include stiffer arteries in some people. So for people who already have an increased risk of heart disease, consulting a doctor before starting a keto diet (and being regularly monitored while you’re on it) remains crucial.

What it may come down to is what type of fat you’re consuming on keto. Higher intakes of monounsaturated fat (like olive oil and avocado) in the context of a high-fat diet were associated with increased levels of heart-protective HDL cholesterol.

14. How Much Protein Will You Eat on the Keto Diet?

A typical keto diet may include 20 to 25 percent of calories coming from protein, says Keene. One common misconception is that this is a high-protein diet, when in reality it’s moderate in protein. “Too much protein can be converted and broken down as sugar to be used as an energy source,” she says. That will kick the body out of ketosis.

That said, you don’t want to go too low in protein. “You want to be able to stay in ketosis without sacrificing lean body mass (muscle) if you lose weight,” says Whitmire. This can loosely equate to 1.2 to 1.5 g of protein per kilogram of body weight. (The recommended dietary allowance is currently 0.8 g per kilogram of body weight.)

Therefore, a 140-pound woman may aim for 76 to 95 g per day. For reference, 3 oz of chicken breast offers 26 g of protein.

One of the best sources of protein on a keto diet is fatty fish (like salmon or mackerel), says Keene, as it offers a source of heart-healthy protein and omega-3 fatty acids. Eggs are another good choice, as one large egg contains 6 g of protein and 5 g of fat.

While a keto diet may focus on fat, that doesn’t mean you have to eat bacon and sausage all day. There is room for leaner proteins like chicken and cod. Just remember to add fat (for example, roast the chicken with olive oil) to these lower-in-fat sources, she says.

Many cuts of beef are also considered lean (less than 4.5 g saturated fat in 3.5 oz) or extra lean (less than 2 g saturated fat per 3.5 oz) when they contain 10 g or less total fat. These include eye of round roast and steak, sirloin tip side steak, top round roast and steak, bottom round roast and steak, and top sirloin steak.

15. Can the Keto Diet Reverse Type 2 Diabetes?

“Though this isn’t the first tool I’d use to help someone control their insulin — carb counting, evenly distributing carbs throughout the day, may be easier to commit to — it’s not off the table, especially with stronger emerging research,” says Keene. The keto diet may, in the short term, help people with type 2 diabetes lose weight, manage blood glucose, and reduce their dependence on medications.

 But looking at the bigger picture, it’s not quite so simple.
Research found that in the short term, the diet eased the workload of insulin-producing cells in the pancreas, helping to lower blood sugar levels. This was largely due to the initial weight loss.

 However, in another study, while up to 62 percent of participants achieved diabetes remission in their first year on a low-carb plan, staying on track long term can be tough. Remission rates dropped to just 13 percent by the fifth year as people stopped keeping up with the strict low-carb diet’s requirements.

Larger, longer-term studies are necessary. Keto can pose health risks to people with diabetes, especially if you’re following it without supervision from a medical professional. Importantly, anyone who is on medication to lower blood sugar or who is using insulin should be aware that drastically cutting carbs can lead to dangerously low blood sugar.

 Unaddressed, this condition, called hypoglycemia, may lead to seizures, loss of consciousness, and blurred vision.

For people with unmanaged type 1 diabetes (and, less often, type 2), entering ketosis increases the rare but possible risk of a life-threatening condition called diabetic ketoacidosis. Talk with your doctor to understand the risk and benefits of starting a restrictive eating pattern like keto if you have diabetes.

Be sure to work with your doctor if you have type 2 diabetes, and manage your expectations. Your diabetes team will be able to work with you on an approach to eating that yields long-term results.

 Also, bear in mind that type 2 diabetes cannot be reversed, but it can be put into remission.

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
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