Keto Promises Fast Weight Loss—But at What Cost?
The ketogenic diet, commonly known as “keto,” has exploded in popularity over the last decade, largely for its promise of quick weight loss. But before keto became a trendy diet, it was actually developed as a medical therapy. Originally used in the 1920s, the ketogenic diet was designed to help manage epilepsy in children who didn’t respond well to medication. In this context, it works by shifting the body into a state called ketosis through a high-fat, very low-carbohydrate eating pattern, altering brain metabolism in a way that helps reduce seizure frequency and severity.
In medical settings, the use of the ketogenic diet is carefully monitored and typically considered when other treatment options have failed. In cases of drug-resistant epilepsy, especially in children, the potential benefits can outweigh the risks. For example, when a child experiences debilitating seizures, the discomfort and side effects of a high-fat, restrictive diet—such as constipation or nutrient deficiencies—may be considered more tolerable than the impact of uncontrolled epilepsy. In these situations, the trade-off is clear. However, this rationale does not apply to weight loss or general health goals, where the risks often outweigh the benefits.
The ketogenic diet can lead to several short-term side effects, including:
Headache
Fatigue
Nausea
Dizziness
Irritability
Brain fog
Constipation
Muscle cramps
Difficulty sleeping
Long-term risks include:
Nutrient deficiencies (fiber, B vitamins, magnesium, potassium, calcium)
Increased LDL cholesterol or triglycerides
Liver strain from increased fat metabolism
Kidney stress from high protein intake
Digestive issues like chronic constipation
Risk of developing an eating disorder from dietary restriction
Bone health concerns
Poor long-term adherence and weight regain
Mood changes due to reduced carbohydrate intake
What many people don’t realize is that the keto diet isn’t a magic solution, and it’s not recommended for sustained weight loss. Studies show that any weight loss on keto is typically due to calorie restriction and water loss from inadequate carbohydrate intake, not because of some special fat-burning state. Even more concerning, weight regain with additional weight gain is common once the diet is stopped, often leading to frustration and confusion. The highly restrictive nature of keto makes it difficult to maintain and can contribute to an unhealthy relationship with food.
In short, while the ketogenic diet has a place in medical nutrition therapy—especially for conditions like epilepsy—it should be approached with caution. For most people looking to lose weight or improve overall health, the discomfort, risks, and long-term sustainability challenges often outweigh any short-term benefits. A more balanced, flexible approach to eating is not only safer but more effective in the long run.
Written by Kim Johnson, RD, LN | Owner
Kim specializes in eating disorders, disordered eating patterns, IBS, nutrition management for neurodivergent individuals (ADD/ADHD and autism spectrum disorder), weight concerns addressed through a weight-inclusive approach, and supporting those ready to move past chronic dieting.