Opinion

Is the Keto Diet Safe? The Benefits Are Real — But So Are the Risks

By Jeff Beck

Note: Author is a Certified Nutritional Coach, and has tried Keto for a year. While he lost over 60 pounds, his cholesterol also spiked!

Few diets inspire arguments quite like keto.

To its supporters, the ketogenic diet is a revolutionary way to lose weight, control hunger and improve blood sugar without counting every calorie. To its critics, keto is an unnecessarily restrictive eating plan that replaces fruits, whole grains and beans with mountains of meat, cheese, butter and bacon while potentially sending cholesterol levels in the wrong direction.

As is often the case in nutrition, reality is considerably less exciting than social media makes it sound.

The available scientific evidence suggests that ketogenic diets can produce genuine benefits, particularly in the short term. They can help some people lose weight, lower triglycerides and improve blood-sugar control. Keto also has legitimate medical applications, most notably in the treatment of certain forms of epilepsy.

But there is another side of the equation that deserves just as much attention. Ketogenic diets can raise LDL cholesterol, can be difficult to sustain, may contribute to nutritional deficiencies and are simply inappropriate for some people.

So, is keto safe?

For many otherwise healthy adults, a carefully designed ketogenic diet can probably be used safely, particularly for a limited period and with appropriate medical oversight. But that is very different from saying keto is the healthiest diet for everyone—or that everyone should stay on it indefinitely.

And that distinction tends to disappear in the diet wars.

What Exactly Is the Keto Diet?

A ketogenic diet severely restricts carbohydrates while dramatically increasing dietary fat.

A typical ketogenic eating plan provides roughly 70% to 80% of calories from fat, 10% to 20% from protein and only about 5% to 10% from carbohydrates. Carbohydrate intake commonly falls below 50 grams per day and sometimes approaches 20 grams.

That is an enormous departure from the way most Americans eat.

Bread, pasta, rice, potatoes, cereal, sweets and sugary drinks are generally eliminated or dramatically restricted. Most fruit, beans and many other carbohydrate-rich foods are limited as well.

The objective is to force the body into a metabolic state known as ketosis.

Normally, the body gets much of its energy from glucose derived from carbohydrates. When carbohydrate availability falls dramatically, insulin levels decrease and the body begins relying much more heavily on stored fat. The liver converts fatty acids into molecules called ketones, which can be used as an alternative energy source.

That metabolic shift is real.

The disagreement is over what it means for long-term health.

The Case for Keto: It Really Can Help People Lose Weight

The most obvious argument for keto is weight loss.

People frequently do lose weight when they drastically reduce carbohydrate intake, particularly during the first several months.

Some of the initial drop comes from water because carbohydrate storage is associated with stored water in the body. But keto can also produce genuine fat loss.

There are several plausible reasons.

High-fat and protein-containing meals can be satiating. Ketosis itself may suppress appetite in some people. Eliminating sugary drinks, desserts, chips, bread and other calorie-dense foods can also substantially reduce calorie intake without requiring someone to consciously count calories.

Randomized-trial research on low-carbohydrate diets has generally found an early weight-loss advantage.

A meta-analysis of 25 randomized trials involving people with obesity found that low-carbohydrate diets produced approximately 2.6 kilograms — about 5.7 pounds — more weight loss than comparison diets at three to four months, with a similar advantage at six to eight months.

That is meaningful.

But here comes the important part.

By approximately 10 to 14 months and again at 18 to 30 months, the advantage disappeared.

This is one of the recurring themes in nutrition research: wildly different diets often produce different short-term results but much smaller differences once you start following people for a year or two.

The best diet eventually becomes the diet someone can actually live with.

Keto Can Improve Triglycerides

One of keto’s strongest arguments involves triglycerides.

High triglyceride levels are associated with cardiovascular and metabolic risk, and ketogenic diets often reduce them substantially.

A large 2026 meta-analysis examining 62 randomized controlled studies found that ketogenic diets reduced triglycerides by roughly 20 mg/dL compared with control diets.

Another recent analysis found a reduction of approximately 22 mg/dL.

That is not insignificant.

Keto also tends to increase HDL cholesterol, traditionally referred to as “good” cholesterol. The 62-study analysis found an average HDL increase of approximately 3.6 mg/dL.

Those results explain why some people can begin keto and watch several numbers on their blood work move impressively in the right direction.

But they should not stop reading the lab report there.

The LDL Cholesterol Problem Cannot Simply Be Ignored

Here is where I become much more cautious about keto.

The same 2026 analysis that found lower triglycerides and higher HDL also found that ketogenic diets increased LDL cholesterol by an average of about 8.5 mg/dL and total cholesterol by about 8 mg/dL compared with control diets.

Another 2026 meta-analysis reported remarkably similar results: LDL increased approximately 8.2 mg/dL, while triglycerides fell about 22 mg/dL.

And yet another recent review involving 24 studies and more than 47,000 participants found an average LDL increase of approximately 12.2 mg/dL, although it also documented improvements in body weight, blood pressure, glucose and triglycerides.

That creates one of the strangest things about keto.

Your blood work can simultaneously look better and worse.

Triglycerides may fall.

HDL may rise.

Blood sugar may improve.

Weight may decline.

And LDL may rise.

For people who already have elevated LDL cholesterol, familial hypercholesterolemia or significant cardiovascular risk, that should not be dismissed simply because other markers look better.

We still do not have enough long-term clinical outcome research showing whether years of ketogenic eating ultimately increases, decreases or leaves cardiovascular events unchanged. Recent researchers have explicitly described that evidence as limited and mixed.

That uncertainty matters.

Not All Keto Diets Are the Same

Perhaps the biggest mistake in discussing keto is pretending there is only one version.

There is an enormous difference between someone getting most of their fat from:

olive oil, avocados, walnuts, almonds, seeds, salmon and other oily fish

and someone getting it primarily from:

butter, bacon, sausage, processed meat, cheese and fatty cuts of red meat.

Both diets might technically produce ketosis.

They are not nutritionally equivalent.

Harvard’s Nutrition Source notes that a ketogenic diet can be modified to emphasize unsaturated fats from foods including olive oil, avocado, nuts, seeds and fatty fish rather than relying heavily on saturated fats.

This is where I believe the online keto conversation goes badly wrong.

Ketosis itself does not magically turn bacon into broccoli.

Food quality still matters.

Keto May Be Useful for People With Type 2 Diabetes

Another promising area involves type 2 diabetes.

Severely restricting carbohydrates can reduce the amount of glucose entering the bloodstream after meals. Some people consequently experience improved glucose control and may require less diabetes medication.

Research has reported improvements in blood sugar, weight and several metabolic measures among people with type 2 diabetes using ketogenic or very-low-carbohydrate diets.

That makes physiological sense.

But anyone taking glucose-lowering medication should not simply decide one Monday morning that carbohydrates are now forbidden.

Medication doses sometimes need adjustment as carbohydrate intake changes. Insulin and medications such as sulfonylureas can cause hypoglycemia if medication and food intake are not appropriately coordinated.

There is also particular concern involving SGLT2 inhibitor drugs, because very-low-carbohydrate diets can contribute to circumstances that increase the risk of a dangerous condition called euglycemic diabetic ketoacidosis.

For someone with diabetes, keto should therefore be a conversation with a physician—not an experiment dictated by a TikTok video.

Nutritional Ketosis Is Not the Same as Diabetic Ketoacidosis

This distinction deserves emphasis because the terminology understandably confuses people.

Nutritional ketosis occurs when carbohydrate intake becomes sufficiently low that the body increases production of ketones.

Diabetic ketoacidosis, or DKA, is an entirely different and potentially life-threatening condition involving excessive ketone accumulation, metabolic acidosis and inadequate insulin activity.

Healthy people entering ordinary nutritional ketosis generally maintain enough insulin activity to prevent ketones from rising to dangerous levels.

People with type 1 diabetes, however, require considerably more caution.

Research examining ketogenic diets in type 1 diabetes has reported possible improvements in glucose control but also concerns surrounding hypoglycemia, abnormal cholesterol and diabetic ketoacidosis.

That is not a population in which I would recommend experimenting with keto without close medical supervision.

Keto Has One Medical Use That Is Not a Fad

It is also important to recognize that ketogenic diets did not begin as an Instagram weight-loss trend.

They have been used medically for roughly a century to treat epilepsy.

The Epilepsy Foundation reports that ketogenic dietary therapy can substantially reduce seizures in some children whose seizures do not respond adequately to medication. More than half can experience at least a 50% reduction in seizures, while approximately 10% to 15% may become seizure-free.

That is a legitimate therapeutic intervention.

But notice how medical ketogenic therapy is used.

It is carefully prescribed.

Food is measured.

Nutrition is monitored.

Patients are supervised by clinicians and dietitians.

That is a very different model from someone seeing a social-media influencer fry six eggs in bacon grease and deciding carbohydrates are poison.

The Kidney-Stone Risk Is Real

Kidney stones represent another potential concern.

A systematic review and meta-analysis involving 36 studies and 2,795 people following ketogenic diets found an estimated kidney-stone incidence of approximately 5.9% over an average follow-up of roughly 3.7 years.

The estimated incidence among adults was approximately 7.9%, although the confidence interval was wide because fewer adult data were available.

That does not mean someone who tries keto has an 8% guaranteed chance of developing kidney stones.

The studies included medically supervised ketogenic therapy populations and varied considerably.

But it does mean kidney-stone risk deserves more attention than it generally receives in diet advertisements.

People with existing kidney disease require additional caution. Reviews have raised concerns about acid load, kidney stones, saturated-fat intake and uncertain long-term safety among people with chronic kidney disease.

Nutrient Deficiencies Are Possible

Another issue is what keto removes.

A strict ketogenic diet can dramatically restrict:

whole grains,

beans and lentils,

many fruits,

starchy vegetables

and various other carbohydrate-containing foods.

Those foods happen to supply fiber, potassium, magnesium, B vitamins and an enormous range of beneficial plant compounds.

Harvard notes that poorly designed ketogenic diets may produce deficiencies in fiber, B vitamins and minerals including iron, magnesium and zinc.

Constipation is also unsurprisingly common when people replace oatmeal, beans, fruit and whole grains with cheese and meat.

Again, keto can be designed intelligently.

Low-carbohydrate vegetables, seeds, nuts, avocados and carefully selected foods can provide substantial nutrition.

But “low carbohydrate” does not automatically mean “healthy.”

Neither does “high fat.”

Then There Is the Infamous “Keto Flu”

People beginning keto commonly describe headaches, fatigue, irritability, brain fog, constipation or weakness during the first several days.

The phrase “keto flu” is not a formal medical diagnosis, but the symptoms are real enough.

A sudden reduction in carbohydrate intake causes changes in stored glycogen, water balance and electrolytes. Harvard notes that fatigue, headache, irritability, constipation, hunger and cognitive fog can accompany the early stages of extreme carbohydrate restriction.

For many people those symptoms improve.

For others, they are the first sign that eating almost no carbohydrates is going to be miserable.

Which brings us to the most underestimated variable in every diet debate.

Can You Actually Live Like This?

It doesn’t matter whether keto produces spectacular results for eight weeks if somebody abandons it in week nine.

Long-term adherence to very-low-carbohydrate diets is difficult for many people.

Birthday cake contains carbohydrates.

Beer contains carbohydrates.

Pizza contains carbohydrates.

Fruit contains carbohydrates.

Thanksgiving dinner contains carbohydrates.

So does practically every restaurant menu you’ve ever seen.

Food is not merely fuel. It is part of family, culture, celebrations, travel and social life.

A diet that makes someone afraid of an apple because it contains sugar may technically produce ketosis, but that does not automatically make it a good long-term relationship with food.

This may help explain why keto’s early weight-loss advantage tends to shrink dramatically over time.

The American Heart Association Is Not Sold on Keto

The American Heart Association evaluated several popular dietary patterns against its recommendations for cardiovascular health.

Mediterranean, DASH, pescatarian and vegetarian eating patterns ranked near the top.

Ketogenic and Paleo diets ranked near the bottom because their restrictions conflict with several elements of the organization’s heart-healthy dietary guidance.

That does not prove keto is dangerous.

It does tell us that anyone claiming keto is unquestionably the healthiest way humans can eat is getting considerably ahead of the scientific consensus.

And there are alternatives.

A moderately lower-carbohydrate diet that still contains fruits, vegetables, legumes and some whole grains may capture many of the advantages of carbohydrate reduction without requiring full nutritional ketosis.

Harvard notes that moderately low-carbohydrate dietary patterns can support cardiovascular health when the protein and fats consumed come primarily from healthy sources.

That seems like an important middle ground.

Who Should Be Particularly Careful With Keto?

Recent clinical reviews recommend additional caution for people with conditions including advanced liver or kidney disease, acute pancreatitis, familial hypercholesterolemia, gallbladder problems, electrolyte disturbances and certain metabolic disorders. Pregnancy, breastfeeding, being underweight and taking certain diabetes or blood-pressure medications also warrant medical guidance before beginning a ketogenic diet.

People with type 1 diabetes deserve particular caution because of the potential risks of hypoglycemia and ketoacidosis.

Anyone taking prescription medication should consider discussing substantial dietary changes with a qualified healthcare professional.

Changing your diet can sometimes change what your medication does.

The Bigger Problem Is Our Obsession With Diet Extremes

This is where my opinion comes into the discussion.

Americans seem incapable of discussing nutrition without eventually declaring an entire macronutrient guilty of crimes against humanity.

For decades, fat was the enemy.

Supermarket shelves filled with low-fat products, many of which substituted refined carbohydrates and sugar for the missing fat.

Then the pendulum swung.

Suddenly carbohydrates became the villain.

Bread was poison.

Fruit had “too much sugar.”

Eating butter became somehow more virtuous than eating beans.

Neither extreme makes much sense.

There are terrible carbohydrates.

There are excellent carbohydrates.

There are terrible fats.

There are excellent fats.

A doughnut and a bowl of lentils both contain carbohydrates. Nutritionally, that tells you almost nothing about whether they are equally healthy.

Likewise, extra-virgin olive oil and processed bacon both contain large amounts of fat.

Again, that does not make them equivalent foods.

The quality of the food matters at least as much as the macronutrient label attached to it.

So, Is Keto Safe?

My answer is yes—with a very large asterisk.

For many otherwise healthy adults, a well-formulated ketogenic diet can probably be followed safely, particularly in the short term.

The evidence suggests legitimate potential benefits:

weight loss,

reduced appetite for some people,

lower triglycerides,

higher HDL cholesterol,

improved blood-sugar control

and established therapeutic benefits in certain epilepsy patients.

But there are legitimate drawbacks as well:

LDL cholesterol can rise,

long-term cardiovascular outcome data remain limited,

kidney stones can occur,

nutritional deficiencies are possible,

constipation and early side effects are common,

medication interactions matter

and maintaining the diet can be extremely difficult.

Weight Loss Diminishing Returns

Most importantly, keto’s weight-loss superiority appears to diminish substantially over time.

That leads me to a conclusion that is considerably less marketable than “CARBS ARE KILLING YOU” or “KETO WILL DESTROY YOUR HEART.”

Keto is a tool.

For the right person, used intelligently, it can be a useful one.

For the wrong person—or when transformed into an excuse to eat unlimited processed meat, butter and cheese—it can become a poor nutritional strategy.

There is also very little evidence that the average person needs to live in permanent ketosis to be healthy.

For many people, the more sustainable approach may be considerably less dramatic: eat fewer refined carbohydrates and sugary foods, consume more vegetables and minimally processed foods, prioritize unsaturated fats, eat adequate protein, maintain an appropriate calorie intake and choose an eating pattern you could realistically follow five years from now.

Because the most successful diet isn’t necessarily the one that produces the most dramatic transformation after six weeks.

It is the one that improves your health without requiring you to spend the rest of your life fighting your dinner plate.

Medical note: This article is intended for general informational and opinion purposes and is not individualized medical advice. People with diabetes, kidney or liver disease, cardiovascular risk, pregnancy, eating-disorder concerns or prescription medications should discuss major dietary changes with an appropriate healthcare professional.

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