| Definition |
Very low-carb, high-fat diet (typically <50g carbs/day) that induces ketosis. |
Moderately reduces carbohydrate intake (50–150g carbs/day) without necessarily inducing ketosis. |
Eating pattern alternating between periods of fasting and eating (e.g., 16:8). |
| Primary Mechanism |
Lowers insulin levels by minimising carb intake and shifting metabolism to fat/ketone use. |
Reduces insulin spikes by lowering carb load but still allows some carbs. |
Prolonged fasting lowers insulin levels and improves insulin sensitivity during fasting periods. |
| Impact |
Strong evidence for improving insulin sensitivity and lowering blood sugar, especially in type 2 diabetes. |
Improves insulin sensitivity, but effects may be milder compared to keto. |
Can significantly improve insulin sensitivity by extending periods of low insulin. |
| Ease of Adoption |
Often challenging due to strict carb restriction and diet change. |
Easier to maintain long term than keto because it is less restrictive. |
Variable; easier for some, but fasting periods may be hard for others. |
| Typical Side Effects |
Keto flu, nutrient deficiencies if poorly planned, potential lipid changes. |
Fewer side effects, but may still cause fatigue or nutrient imbalance if not balanced. |
Hunger, irritability, risk of overeating during eating windows, not suitable for everyone. |
| Sustainability |
Difficult for many people to sustain long term. |
More sustainable than keto for most individuals. |
Sustainability varies; may be easier than keto for some. |
| Best Suited For |
Those who can adhere to strict carb restriction and want rapid metabolic improvements. |
Individuals seeking moderate carb reduction with fewer dietary restrictions. |
People comfortable with meal timing changes rather than strict food restrictions. |
| Scientific Evidence |
Substantial evidence for short-term benefits in blood sugar control; long-term data are limited and mixed. |
Good evidence for improving metabolic health; long-term outcomes generally favourable if diet quality is high. |
Growing evidence supports benefits for insulin sensitivity and weight loss; long-term effects still under investigation. |
| Effects on Weight and Health |
Often leads to rapid weight loss initially, but maintaining weight loss long term is challenging; long-term cardiovascular effects are debated. |
Promotes steady weight loss with better long-term adherence; associated with improved metabolic health if done with whole foods. |
Can support weight loss and metabolic health, but effectiveness depends heavily on diet quality during eating windows and consistency. |