The ketogenic diet is one of the most searched and debated dietary approaches of the past decade. Unlike many diet trends, it has genuine medical origins and legitimate research behind it. But that doesn't mean it's right for everyone.
This guide covers what keto actually involves, what the science says, and how to determine if it might suit your goals.
What Is the Keto Diet?
The ketogenic diet is a very low-carbohydrate, high-fat eating pattern designed to shift your body's primary fuel source from glucose (carbohydrates) to ketones (derived from fat).
The standard ketogenic diet typically follows this macronutrient breakdown:
In practical terms, this means limiting carbohydrates to around 20-50 grams per day - roughly the amount in a single banana or slice of bread. Most of your calories come from fat sources like oils, nuts, avocados, and fatty fish.
The Medical Origins
Keto wasn't invented as a weight loss diet. It was developed in the 1920s as a treatment for epilepsy, particularly in children who didn't respond to medication. Doctors observed that fasting reduced seizures, and the ketogenic diet was designed to mimic the metabolic effects of fasting without actual starvation.
The diet fell out of favour as anti-epileptic drugs improved, but has experienced a resurgence since the 1990s - both for epilepsy and, increasingly, for metabolic conditions and weight loss.
Key Point
Unlike many trendy diets, keto has nearly 100 years of clinical use. This doesn't mean it's appropriate for everyone, but it does mean the physiological effects are well-documented.
How Ketosis Works
When you drastically reduce carbohydrate intake, your body depletes its stored glucose (glycogen) within 2-4 days. Without glucose readily available, the liver begins converting fatty acids into molecules called ketones, which can fuel most of your cells and organs - including your brain.
This metabolic state is called ketosis. Signs you've entered ketosis may include:
- Reduced appetite (a common early effect)
- Increased thirst and urination
- Temporary "keto breath" (a fruity or metallic smell)
- Initial fatigue followed by sustained energy
Nutritional ketosis (blood ketone levels of 0.5-3.0 mmol/L) is distinct from diabetic ketoacidosis, a dangerous condition in type 1 diabetes. In healthy individuals, the body regulates ketone production to safe levels.
What the Research Shows
Keto has been studied for multiple conditions. Here's what the evidence actually supports:
Weight Loss: Moderate Evidence
Short-term studies (6-12 months) consistently show greater weight loss on keto compared to low-fat diets. A 2013 meta-analysis in the British Journal of Nutrition found ketogenic diets produced greater weight loss than conventional low-fat diets. However, long-term studies (2+ years) show the difference often diminishes, suggesting adherence challenges.
Blood Sugar Control: Strong Evidence
For people with type 2 diabetes or prediabetes, low-carb and ketogenic diets can significantly improve blood glucose control. A 2017 review in Diabetes Research and Clinical Practice found carbohydrate restriction was particularly effective at reducing HbA1c levels. Some patients are able to reduce or eliminate diabetes medication under medical supervision.
Epilepsy: Strong Evidence
Keto remains a recognised treatment for drug-resistant epilepsy. Studies show it can reduce seizure frequency by more than 50% in approximately half of children who try it. The mechanism isn't fully understood but likely involves ketones' effects on brain energy metabolism.
Appetite Suppression: Moderate Evidence
Multiple studies show ketogenic diets reduce perceived hunger, potentially due to the appetite-suppressing effects of ketones and the satiating nature of protein and fat. This may make calorie restriction easier for some people.
Potential Benefits and Drawbacks
Potential Benefits
- Effective for short-term weight loss
- May reduce appetite and cravings
- Can improve blood sugar control
- Some people report improved mental clarity
- Forces elimination of ultra-processed foods
- No calorie counting required for some
Potential Drawbacks
- Highly restrictive - hard to maintain long-term
- "Keto flu" during adaptation (headaches, fatigue)
- May be low in fibre without careful planning
- Social and practical challenges
- Risk of nutrient deficiencies
- Not suitable for some medical conditions
Common Mistakes on Keto
Many people who "fail" at keto make these avoidable errors:
- Not eating enough vegetables - Keto should include low-carb vegetables (leafy greens, broccoli, cauliflower). Meat and cheese alone won't cut it.
- Fear of all carbs - You're not aiming for zero carbs. 20-50g of carbs from vegetables is both allowed and beneficial.
- Ignoring electrolytes - Lower insulin levels on keto cause increased sodium excretion. You may need more salt, potassium, and magnesium.
- Too much protein - Excessive protein can be converted to glucose, potentially limiting ketosis. Moderate protein is the goal.
- Expecting immediate results - Initial weight loss is largely water. True fat adaptation takes 2-4 weeks.
Who Should Avoid Keto
Keto is not appropriate for everyone. Those with type 1 diabetes, liver or kidney disease, history of eating disorders, or who are pregnant or breastfeeding should avoid ketogenic diets or only try them under close medical supervision. Always consult a healthcare professional before making significant dietary changes.
Is Keto Right for You?
Keto may suit you if:
- You respond well to structured eating rules
- You have significant weight to lose or blood sugar issues
- You don't mind limiting carbohydrate-rich foods long-term
- You've tried other approaches without success
- You can commit to proper planning and monitoring
Keto probably isn't for you if:
- You struggle with restrictive eating or have a history of disordered eating
- You're an endurance athlete requiring high carbohydrate intake
- You can't imagine giving up bread, pasta, or fruit long-term
- You prefer flexibility in your eating
- You have any of the medical conditions mentioned above
The Bottom Line
The ketogenic diet is a legitimate therapeutic approach with genuine research support - not just another fad. But it's also highly restrictive and not superior to other dietary approaches for most people. The best diet is the healthy one you can actually sustain. If keto works for you, great. If it feels unsustainable, there are equally effective alternatives.
A Practical Approach
If you're curious about lower-carb eating but intimidated by strict keto, consider a moderate approach first. Reducing carbohydrates to 50-100g per day captures many of the benefits without the extreme restriction. You can always go stricter if needed.
Focus on food quality regardless of macros: vegetables, adequate protein, healthy fats, minimal ultra-processed foods. These principles matter more than hitting exact ketone levels.
← Back to Different DietsReferences
- Zhou, C., et al. (2022). Ketogenic Diet Benefits to Weight Loss, Glycemic Control, and Lipid Profiles in Overweight Patients with Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trials. International Journal of Environmental Research and Public Health, 19(16), 10429. doi:10.3390/ijerph191610429
- Silverii, G.A., et al. (2022). Effectiveness of low-carbohydrate diets for long-term weight loss in obese individuals: A meta-analysis of randomized controlled trials. Clinical Nutrition ESPEN, 51, 51-64. doi:10.1016/j.clnesp.2022.08.004
- Malinowska, D., et al. (2024). Ketogenic Diet: A Review of Composition Diversity, Mechanism of Action and Clinical Application. Journal of Nutrition and Metabolism, 2024, 6666171. doi:10.1155/2024/6666171
- Kossoff, E.H., et al. (2018). Optimal clinical management of children receiving dietary therapies for epilepsy. Epilepsia Open, 3(2), 175-192. doi:10.1002/epi4.12225
- Zhu, H., et al. (2022). Ketogenic diet for human diseases: the underlying mechanisms and potential for clinical implementations. Signal Transduction and Targeted Therapy, 7, 11. doi:10.1038/s41392-021-00831-w
