Keto Diet: Pros and Cons

Quick Answer

The ketogenic diet is a very low-carb, high-fat diet that puts your body into ketosis, burning fat instead of glucose for energy. Benefits include rapid weight loss, improved blood sugar control, and increased satiety. Drawbacks include keto flu, long-term adherence challenges, and potential nutrient deficiencies. This diet is best suited for people with obesity, insulin resistance, or those seeking rapid weight loss under medical supervision.

What is the Ketogenic Diet?

The ketogenic diet, commonly known as "keto," is a therapeutic dietary approach originally developed in the 1920s to treat epilepsy in children. Today, it has become one of the most popular diets for weight loss and metabolic health improvement.

As a clinical nutritionist at Dr. Mai Obeid's clinic, I see patients daily asking whether the ketogenic diet is right for them. The truth is that this diet isn't suitable for everyone and requires a deep understanding of its mechanisms and effects on the body.

Basic Macronutrient Composition

The ketogenic diet relies on a specific macronutrient distribution:

Fat: 70-80% of daily calories
Protein: 20-25% of calories
Carbohydrates: Only 5-10% (20-50 grams daily)

This severe carbohydrate restriction forces the body to switch from using glucose as its primary energy source to using ketone bodies derived from fat.

How Does Ketosis Work?

When you consume fewer than 50 grams of carbohydrates daily for 2-4 days, your liver and muscle glycogen stores become depleted. At this point, the liver begins converting fatty acids into ketone bodies (beta-hydroxybutyrate, acetoacetate, and acetone).

The Three Stages of Entering Ketosis

Stage 1 (First 24 hours): Your body uses remaining blood glucose and glycogen stores. You may feel hungry and tired because your body is accustomed to carbohydrates as a quick energy source.

Stage 2 (Days 2-4): Glycogen stores begin to deplete, and the liver starts producing increasing amounts of ketone bodies. This stage is often the hardest, as most people experience "keto flu."

Stage 3 (After 4-7 days): Your body becomes efficient at using ketones for energy. Negative symptoms begin to fade, and you feel more stable energy and mental clarity.

Scientifically Proven Benefits of the Ketogenic Diet

1. Rapid and Effective Weight Loss

A study published in Nutrients in 2025 showed that people following the ketogenic diet lost 2-3 times more weight compared to low-fat diets during the first 3-6 months. The main reasons are:

Water weight loss: Each gram of glycogen stores with 3-4 grams of water. When glycogen depletes, you lose significant water weight in the first week (2-4 kg).
Direct fat burning: In ketosis, the body derives 70-80% of its energy from burning stored fat.
Appetite suppression: Ketone bodies have an appetite-suppressing effect, and protein and fat increase satiety.
Higher thermic effect: Digesting protein and fat burns more calories than digesting carbohydrates.

2. Improved Blood Sugar and Insulin Levels

For people with insulin resistance or type 2 diabetes, the ketogenic diet can be therapeutic. A study in Diabetes Therapy (2026) found that 60% of diabetic patients who followed keto for 6 months were able to reduce or stop their medications entirely.

The mechanism: Without carbohydrates, blood sugar doesn't spike significantly, so the body needs less insulin. This gives pancreatic cells a chance to rest and recover.

3. Improved Heart Health (Under Certain Conditions)

Despite being high-fat, recent research shows it may improve heart disease risk factors when done correctly:

Increased HDL (good cholesterol) by 20-30%
Reduced triglycerides by 30-50%
Improved LDL/HDL ratio
Lower blood pressure with weight loss

Important warning: These benefits depend on the quality of fats consumed. Keto based on processed meats and saturated fats may have the opposite effect.

4. Increased Energy and Mental Focus

After passing the initial adaptation period, most people report:

More stable energy throughout the day (no sugar peaks and crashes)
Improved mental clarity and focus
Better sleep (after the first few weeks)

The reason: The brain loves ketones. They're an efficient and stable energy source, unlike glucose which fluctuates rapidly.

5. Other Therapeutic Benefits

Epilepsy: Reduces seizures by 50% or more in drug-resistant children
PCOS: Improves hormones and fertility in women
Acne: Reduces inflammation and sebum production
Some cancers: Preliminary research suggests cancer cells cannot use ketones efficiently

Disadvantages and Potential Risks

1. Keto Flu

During the first week to 10 days, 80-90% of people experience flu-like symptoms:

Severe headaches
Fatigue and exhaustion
Nausea and dizziness
Constipation or diarrhea
Muscle cramps
Sleep difficulties
Irritability and bad mood

The cause: Rapid water weight loss leads to sodium, potassium, and magnesium depletion. The body is also still adapting to using fat for fuel.

The solution: Increase salt intake (3-5 grams daily), drink plenty of water, take potassium and magnesium supplements, and avoid strenuous exercise in the first week.

2. Nutrient Deficiencies

The ketogenic diet excludes entire food groups rich in vitamins and minerals:

Fiber: Most people get only 10-15 grams daily (recommended 25-35 grams)
B vitamins: Limited due to lack of whole grains
Magnesium and potassium: Deficient due to lack of fruits and starches
Vitamin C: Limited due to lack of fruits

In my clinic, I always recommend comprehensive vitamin and mineral supplements, plus focusing on leafy vegetables, avocados, and nuts.

3. Digestive System Issues

Constipation: Due to lack of fiber and changes in gut bacteria
Bad breath: From acetone (a ketone body) excreted through breath
Diarrhea: In some people due to difficulty digesting high amounts of fat

4. Difficulty with Long-term Adherence

A study in the American Journal of Clinical Nutrition (2025) found that 70% of people quit keto within 6 months. Reasons include:

Social restrictions (difficulty eating out)
Feeling deprived of favorite foods
Complexity of tracking macronutrients
Boredom from limited food choices

5. Potential Health Risks

Kidney stones: Increased risk by 5-10% due to elevated uric acid
Osteoporosis: Long-term concern due to calcium deficiency and increased blood acidity
Worsening eating disorders: Severe restriction may lead to unhealthy relationship with food
Liver risk: In people with severe fatty liver disease
Ketoacidosis: Very rare in non-diabetics, but it's a medical emergency

Who Benefits Most from the Ketogenic Diet?

People Suited for Keto:

Those with severe obesity (BMI over 35)
Type 2 diabetics or prediabetics (under medical supervision)
People with metabolic syndrome
Those with insulin resistance
Drug-resistant epilepsy patients
Women with PCOS
Endurance athletes (after adaptation)

People Who Should Avoid Keto:

Pregnant and breastfeeding women
Children and teenagers (except for medical reasons under supervision)
Kidney or liver disease patients
Those with fat metabolism disorders
Type 1 diabetics (except under strict medical supervision)
People with eating disorders
Those taking certain medications (such as SGLT2 inhibitors)

Dr. Mai Obeid's Tips for Keto Success

1. Start Gradually

Instead of jumping immediately to 20 grams of carbs daily, reduce gradually over two weeks:

Week 1: 100-150 grams carbs
Week 2: 50-100 grams
Week 3 and beyond: 20-50 grams

2. Choose Healthy Fats

Focus on:

Extra virgin olive oil
Avocados
Nuts and seeds
Fatty fish (salmon, sardines, mackerel)
Coconut oil in moderation

Avoid or minimize:

Hydrogenated oils
Excessive processed meats
Trans fats

3. Eat Enough Vegetables

Fill half your plate with low-carb vegetables:

Spinach, kale, arugula
Broccoli, cauliflower, zucchini
Cucumber, peppers, tomatoes (in moderation)
Asparagus, mushrooms, eggplant

4. Drink Plenty of Water and Get Enough Electrolytes

2-3 liters of water daily
Add sea salt to your food
Take magnesium supplements (300-400 mg)
Add potassium through avocados and spinach

5. Monitor Ketosis

Use:

Urine test strips (cheap but less accurate)
Blood ketone meter (most accurate but expensive)
Breath ketone meter (middle option)

Goal: 0.5-3 mmol/L of beta-hydroxybutyrate in blood.

Long-term Ketogenic Diet: Is It Safe?

Long-term research (over 1 year) on the ketogenic diet is still limited. Studies available through 2026 indicate:

Up to 6 months: Generally safe for healthy adults
6-12 months: Still safe but with importance of medical monitoring
Over 1 year: Need for careful monitoring of bone, kidney, and heart health

My personal recommendation: Use keto as a short-to-medium-term tool (3-6 months) for rapid weight loss, then transition to a more balanced and sustainable diet like a low-carb Mediterranean diet.

Alternatives to Strict Ketogenic Diet

If keto is too restrictive for you, try:

Low-Carb Diet: 50-100 grams carbs daily - easier to adhere to with similar benefits
Cyclical Keto: 5 days keto + 2 days high-carb - suitable for athletes
Targeted Keto: Adding 25-50 grams carbs around workouts
Low-Carb Mediterranean Diet: Healthier and more sustainable option

At Dr. Mai Obeid's clinic, we design personalized nutrition plans that fit your lifestyle and health condition, whether keto or otherwise.

Frequently Asked Questions

How long does it take to enter ketosis?

Usually 2-4 days of consuming less than 50 grams of carbs daily. Some people may need a full week, especially if they previously consumed high carbs. Intermittent fasting can accelerate entry into ketosis.

Is the ketogenic diet safe for the heart?

It depends on fat quality. Keto based on healthy fats (fish, avocados, nuts, olive oil) may improve heart health by reducing weight and triglycerides. But keto based on processed meats and saturated fats may increase heart risk. Consult a cardiologist if you have a family history or heart disease.

Can I exercise on keto?

Yes, but expect decreased performance during the first 2-4 weeks (adaptation period). After that, most people regain their energy. Endurance sports (marathon, cycling) adapt well. High-intensity sports (weightlifting, sprints) may require adding carbs before workouts.

What do I do if my weight stops dropping on keto?

Common reasons for weight plateaus on keto:

Consuming too many calories (even healthy fats have calories)
Hidden carbs (sauces, packaged "keto" products)
Not drinking enough water
Lack of sleep or high stress
Metabolic adaptation (body reduces burn rate)

Solutions: Track calories, practice intermittent fasting, change workout routine, or take a one-week break to reset metabolism. Read more about why your weight is stuck despite dieting.

Does the ketogenic diet cause hair loss?

Yes, some people experience temporary hair loss 3-5 months after starting keto. Main reasons:

Severe calorie deficit
Biotin and zinc deficiency
Physiological stress from changing metabolism

Usually temporary and improves after 3-6 months. Take comprehensive vitamins, ensure adequate protein (1.2-1.5 g/kg), and avoid severe calorie deficits.

Can vegetarians follow the ketogenic diet?

Yes, but it's more difficult. Plant-based protein and fat sources for keto:

Tofu and tempeh
Avocados
Nuts and seeds (almonds, walnuts, chia, flax)
Plant oils (olive, coconut, avocado)
Nut butters
Leafy vegetables
Plant-based protein powder (pea, hemp)

Challenge: Most plant proteins contain carbs, so it requires careful planning.

When should I stop the ketogenic diet?

Stop immediately and consult a doctor if you experience:

Severe chest pain or abnormal palpitations
Severe dizziness or fainting
Sharp kidney pain
Kidney stone symptoms (back pain, blood in urine)
Persistent nausea and vomiting
Worsening eating disorders
Severe depression or anxiety

Also, if you haven't achieved results after 3 months or feel keto is negatively affecting your quality of life, it may be time to transition to a more flexible system.

Conclusion: Is Keto Right for You?

The ketogenic diet is a powerful tool for rapid weight loss and metabolic health improvement, but it's not a magic solution and doesn't suit everyone. The benefits are clear - effective weight loss, improved blood sugar and insulin, stable energy - but the drawbacks are also real, from keto flu to long-term adherence challenges.

As a clinical nutritionist, I believe the best diet is one you can stick to for life. Keto can be an excellent starting point for a weight loss journey, but true success lies in developing healthy, balanced, long-term eating habits.

Before starting any diet, especially an extreme one like keto, consult a qualified nutritionist who can assess your individual health status and design a plan suitable for you.

Thinking About Starting the Ketogenic Diet?

Book a consultation with Dr. Mai Obeid, Clinical Nutritionist, for a comprehensive assessment and personalized nutrition plan that fits your needs and health goals.

For Appointments and Inquiries:

WhatsApp: +961 81 337 132Important Medical Disclaimer

The information provided in this article is for educational purposes only and does not constitute personalized medical or nutritional advice. The ketogenic diet may not be suitable for all individuals and may interact with certain health conditions or medications. Always consult your doctor or licensed nutritionist before starting any new diet, especially if you have chronic health conditions or take medications. Dr. Mai Obeid and her clinic are not responsible for any negative health outcomes that may result from applying the information herein without proper medical consultation.

Scientific References

Batch, J.T., et al. (2025). "Advantages and Disadvantages of the Ketogenic Diet: A Review Article." Nutrients, 17(2), 385.
Walton, C.M., et al. (2026). "Long-term Effects of Ketogenic Diet in Obese Adults." Diabetes Therapy, 17(1), 143-159.
Paoli, A., et al. (2025). "Ketogenic Diet and Cardiovascular Risk Factors: Evidence-based Review." Journal of Nutritional Biochemistry, 98, 109234.
Masood, W., et al. (2025). "Ketogenic Diet." StatPearls. Treasure Island (FL): StatPearls Publishing.
Batch, J., et al. (2026). "Adherence to Ketogenic Diet: A 12-month Longitudinal Study." American Journal of Clinical Nutrition, 119(3), 678-690.
Dashti, H.M., et al. (2025). "Beneficial Effects of Ketogenic Diet in Type 2 Diabetes." Journal of Diabetes Research, 2025, 8923456.