What the keto diet actually is
Before you can take advantage of keto diet benefits, you need a clear picture of what you are signing up for.
On a classic ketogenic diet, you typically:
- Keep carbs very low, often under 20 to 50 grams per day
- Get about 70 to 80% of your calories from fat
- Fill the rest of your calories with protein
By limiting carbohydrates, you push your body into ketosis, a metabolic state where you burn fat for energy instead of relying on glucose from carbs. Your liver turns fat into ketone bodies, which your brain and muscles can use as fuel (Harvard T.H. Chan School of Public Health).
Originally, this way of eating was designed in the 1920s to help children with epilepsy control seizures. Today, it is widely promoted for weight loss, blood sugar control, and other health goals (Northwestern Medicine).
How keto diet benefits weight loss
If your main goal is to lose weight, several features of keto can make that easier, especially in the short term.
You usually lose weight quickly at first
When you first start keto, you often see the scale move fast. This happens for two reasons:
- Glycogen and water loss: Your body stores carbs as glycogen, and glycogen holds water. When carbs drop, glycogen and the attached water drop too, so you lose several pounds quickly.
- Increased fat burning: Once you are in ketosis, your body taps into fat stores for energy instead of relying on carbs.
Short-term studies show that ketogenic diets lead to weight loss and improvements in conditions linked to excess weight, such as insulin resistance and blood pressure (Harvard T.H. Chan School of Public Health).
Experts also note that people often feel less hungry on keto compared with other calorie-restricted plans. This is partly due to steady blood sugar and a higher intake of protein and fat, which are more filling (Northwestern Medicine).
You may burn more fat and reduce belly weight
Several clinical studies indicate that ketogenic diets reduce:
- Overall body weight
- Body fat
- Visceral abdominal fat (the deeper belly fat linked with health risks)
Some research suggests fat loss on keto can be equal to or greater than that on low-fat diets over periods from weeks up to about two years (PMC-NCBI).
However, after about a year, the total weight loss from keto is often similar to what you see with other structured weight-loss diets, which means long-term success still depends on consistency and overall calorie balance (Harvard T.H. Chan School of Public Health).
You often feel less hungry
Hunger makes many diets hard to follow. Keto diet benefits include appetite changes that may make it easier for you to stay on track, such as:
- Reduced cravings for sugary foods
- More stable energy, so you are not constantly chasing a snack
- A feeling of fullness from higher protein and fat intake
People in ketogenic diet studies frequently report reduced hunger compared with other restrictive diets (Northwestern Medicine). Stable hunger levels can be a real advantage if you have struggled with constant snacking in the past.
Metabolic benefits beyond the scale
Keto diet benefits are not only about weight loss. Many people adopt keto to improve metabolic health, especially if they have high blood sugar, insulin resistance, or Type 2 diabetes.
Better blood sugar and insulin control
For some people, especially those with Type 2 diabetes or prediabetes, keto can significantly lower blood sugar. By drastically reducing carb intake, you reduce the need for insulin, which may help:
- Lower hemoglobin A1c (HbA1c)
- Improve insulin sensitivity
- Reduce or even eliminate the need for diabetes medications in some patients
A review of clinical studies found that ketogenic diets helped patients with diabetes lower HbA1c and cut back on or stop insulin use in some cases (PMC-NCBI).
The Cleveland Clinic also notes that keto can lower blood glucose and promote weight loss in people with Type 2 diabetes, although long-term safety is still being studied (Cleveland Clinic).
If you use insulin or other diabetes drugs, you must work closely with your healthcare provider, because keto can increase the risk of low blood sugar if medications are not adjusted.
Improvements in metabolic syndrome
If you have a cluster of issues such as abdominal obesity, high blood pressure, and abnormal cholesterol, you may meet the criteria for metabolic syndrome.
In a pilot trial from Stanford Medicine that followed people with serious mental illnesses on antipsychotic medications, participants who followed a ketogenic diet for about four months saw:
- Complete resolution of metabolic syndrome in those who had it at the start
- Average weight loss of about 10% of body weight
- Reduced waist circumference and better insulin resistance
- Improvements in blood pressure, triglycerides, and blood sugar (Stanford Medicine)
Although this group had unique health challenges, the results highlight how powerful diet changes like keto can be for metabolic health when supervised and personalized.
Possible improvements in cholesterol and triglycerides
Keto can influence your cholesterol and triglyceride levels in different ways.
Some studies have found that ketogenic diets:
- Lower triglycerides
- Increase HDL cholesterol (the “good” cholesterol)
- In some cases lower LDL cholesterol, although this does not happen for everyone (PMC-NCBI)
However, not all research is consistent. In a study comparing keto with a Mediterranean diet in people with Type 2 diabetes or prediabetes, both diets improved blood glucose and several metabolic markers. Yet:
- The ketogenic diet increased LDL cholesterol
- The Mediterranean diet decreased LDL cholesterol and was easier to maintain long term (Stanford Medicine)
For you, this means it is especially important to choose heart-healthy fats on keto, such as olive oil, avocados, and fatty fish, and to monitor your cholesterol with your healthcare provider, particularly if you already have heart disease risk factors (Northwestern Medicine, Cleveland Clinic).
Brain and mood related benefits
Keto is not just about the number on the scale. Several of the most interesting keto diet benefits show up in your brain and nervous system.
Long history in epilepsy treatment
The ketogenic diet has been used for about a century to reduce seizures in children with epilepsy who do not respond to standard medications. Ketones offer an alternative fuel that appears to stabilize brain activity and reduce seizure frequency (Northwestern Medicine, University of Utah Health).
If you have a seizure disorder, though, you should never try keto on your own. Medical teams typically oversee these diets closely, especially in children.
Emerging support for serious mental illness
Newer research suggests keto might help support brain function in conditions like bipolar disorder and schizophrenia, especially when these patients struggle with weight gain and metabolic problems from antipsychotic medications.
In the 2024 Stanford pilot trial, people with serious mental illnesses followed a ketogenic diet for four months. They experienced:
- About 10% average body weight loss
- Resolution of metabolic syndrome in those who had it at baseline
- Improved blood pressure, triglycerides, blood sugar, and insulin resistance
- A 31% average improvement on a global measure of mental illness, with 75% showing clinically meaningful improvement
- Reports of better sleep, mood, energy, and quality of life (Stanford Medicine)
Researchers believe that providing ketones as an alternative brain fuel may help correct underlying brain energy problems in these conditions.
If you live with a serious mental illness and are curious about keto, it is essential to work with your psychiatrist and a dietitian, since medication changes and close monitoring may be needed.
Potential neuroprotective and anti-inflammatory effects
Research suggests that one of the ketone bodies you produce during ketosis, β-hydroxybutyrate (BHB), may act as a signaling molecule that affects gene expression. It appears to:
- Support neuroprotection
- Reduce inflammation
- Improve mitochondrial function, which is how your cells generate energy
These effects are still being explored but may explain why keto is being studied for neurological conditions and overall brain health (PMC-NCBI).
At this point, conditions like Parkinson’s disease and other neurodegenerative disorders still need more research before keto can be recommended as a standard treatment (Northwestern Medicine).
How keto may help your gut and cells
Beyond weight and blood sugar, keto diet benefits could also show up in your gut microbiome and at the cellular level.
Changes in your gut microbiome
Your gut microbiome is the community of bacteria in your digestive tract. Some research suggests that ketogenic diets:
- Increase the diversity of gut microbes
- Raise the ratio of Bacteroidetes to Firmicutes, a pattern that has been linked to better metabolic health in some studies (PMC-NCBI)
This area is still developing, and your individual response may vary. The quality of your fats and proteins, and how many non-starchy vegetables you eat, also affect your gut health on keto.
Effects on gene expression and aging cells
Keto can influence the epigenome, which is the set of chemical tags that turn genes on or off. BHB seems to act as an inhibitor of certain enzymes that control gene expression, which may support anti-inflammatory pathways and mitochondrial function (PMC-NCBI).
At the same time, newer research in animals raises some caution about doing strict keto without breaks:
- A study led by UT Health San Antonio found that a continuous long-term ketogenic diet in animals could promote cellular senescence, which is the build-up of aged cells, particularly in heart and kidney tissues
- These senescent cells can drive inflammation and may affect organ function
- When the researchers used an intermittent ketogenic diet pattern, with planned breaks or “keto vacations,” the pro-inflammatory effects were prevented
- Some negative effects of the ketogenic pattern were reversible when the diet was stopped (UT Health San Antonio, University of Utah Health)
While these findings are in animals, they hint that cycling on and off keto, instead of staying on it nonstop for years, might be safer for long-term health.
Important risks and side effects to know
Every eating pattern has trade-offs. Understanding the downsides of keto helps you decide if it is a good fit for you and how to approach it more safely.
Short-term side effects when you start
In the first days or weeks of keto, you may notice:
- Fatigue and low energy
- Headaches
- Irritability or “brain fog”
- Nausea or constipation
- Cravings for carbs
These symptoms, often called the “keto flu,” usually improve as your body adapts to using ketones for fuel. Staying hydrated, getting enough electrolytes, and making changes gradually can soften the transition (Harvard T.H. Chan School of Public Health).
Potential long-term issues
Longer-term, keto can come with other concerns, especially if the diet is not carefully planned:
- Kidney stones
- Bone loss and osteoporosis
- Elevated uric acid levels, which can contribute to gout
- Nutrient deficiencies, because you may be eating fewer fruits, legumes, and whole grains that supply fiber and vitamins (Harvard T.H. Chan School of Public Health)
The ultra-low-carb version of keto often reduces your intake of nutrients like fiber and vitamins B6, C, D, and E, as well as thiamin and phosphorus compared with a Mediterranean-style diet (Stanford Medicine).
If you have diabetes and high cholesterol or existing heart disease risk, the higher intake of saturated fat in some keto plans may also be a concern. In those cases, dietitians often favor heart-healthy approaches such as the Mediterranean diet, which emphasizes fruits, vegetables, whole grains, and lean proteins (Cleveland Clinic).
Keto is not automatically better long term
It is easy to assume that because keto works quickly, it must be the best long-term approach. The evidence is more mixed:
- After one year, weight loss and metabolic improvements on keto are often not significantly different from those on other calorie-controlled diets
- In a comparison of keto and Mediterranean diets for people with Type 2 diabetes or prediabetes, both diets controlled blood sugar and supported weight loss, but participants found the Mediterranean diet easier to follow and stayed closer to it over time (Harvard T.H. Chan School of Public Health, Stanford Medicine)
In other words, keto diet benefits are real, but long-term success depends on whether you can sustain the eating pattern or transition smoothly to something more flexible later.
Who might want to be cautious or avoid keto
Keto is not suitable for everyone. You need medical guidance, or sometimes a different approach, if you:
- Take insulin or certain diabetes medications
- Have a history of pancreatitis, kidney disease, or liver disease
- Are pregnant or breastfeeding
- Have a history of disordered eating
- Have very high cholesterol or known heart disease
People with diabetes, in particular, need to monitor for hypoglycemia and work with their healthcare team to adjust medications if they reduce carbs drastically (Cleveland Clinic).
If you are not a good candidate for strict keto, you can still get some of the benefits of fat-burning and mild ketosis through alternatives such as:
- A lower carb, Mediterranean-style diet
- Intermittent fasting that includes balanced meals with fruits, vegetables, whole grains, and legumes during eating windows (Northwestern Medicine)
These may be more sustainable and gentler on your cholesterol levels.
Ways to make keto safer and more effective
If you decide to try keto for its potential benefits, a few strategies can help you protect your health and increase your odds of success.
Focus on whole, nutrient-dense foods
It is possible to do “junk food keto,” but that will not give you the same benefits as a well-planned approach. Try to:
- Choose healthy fats such as extra-virgin olive oil, avocado, nuts, seeds, and fatty fish like salmon and sardines (Northwestern Medicine)
- Limit heavily processed meats and trans fats
- Make non-starchy vegetables the base of most meals for fiber and vitamins
- Include good-quality protein like eggs, poultry, fish, tofu, or tempeh
This style of keto is usually better for your heart and more comfortable for your digestion.
Consider a cyclic or intermittent keto pattern
Based on emerging research, you may not need or want to stay in strict ketosis every day for years.
Animal and cellular studies suggest that:
- Constant, long-term keto could encourage the build-up of aged cells in some organs
- Intermittent ketogenic patterns, with planned breaks, may provide many of the benefits while reducing pro-inflammatory effects (UT Health San Antonio)
With your healthcare provider or dietitian, you could explore:
- Cyclic keto, where you follow keto for several weeks and then add back more healthy carbs for a short time
- A transition from strict keto to a moderate low-carb, Mediterranean-style diet after you reach your initial weight or blood sugar goals
These options can make keto feel more flexible and sustainable.
Work closely with your healthcare team
Before starting keto, especially if you have any medical conditions, check in with:
- Your primary care provider
- A registered dietitian, ideally with experience in low-carb or ketogenic diets
- Your endocrinologist or psychiatrist if you have diabetes or serious mental illness
They can help:
- Decide whether keto is appropriate for you
- Adjust medications to prevent very low blood sugar
- Monitor your cholesterol, kidney function, and bone health over time
- Plan how and when to cycle off keto or reintroduce healthy carbohydrates
Professional guidance helps you capture keto diet benefits while reducing unnecessary risk.
Bringing it all together
Keto diet benefits can be significant, especially if you are looking for:
- Faster early weight loss
- Improved blood sugar and insulin levels
- Better control of metabolic syndrome
- Potential support for brain function in certain conditions
At the same time, strict long-term keto is not automatically better than other diets, and it can come with trade-offs like nutrient gaps, higher LDL cholesterol in some people, and possible long-term risks that are still under study.
If you are curious about keto, you do not have to decide everything at once. You might:
- Talk with your doctor or dietitian about whether keto is appropriate for you.
- Try a time-limited, well-planned keto phase with a focus on whole, nutrient-dense foods.
- Reassess after a few months and decide whether to continue, cycle, or transition to a more moderate, balanced style of eating.
The most important thing is choosing an approach that protects your health and that you can realistically live with. Keto can be one useful tool, and you get to decide how, and whether, it fits into your long-term plan.
About the Author
