December 16, 2025, 10:01 am | Read time: 2 minutes
Low-carb diets are trending because many people hope for weight loss or health benefits. A meta-analysis examined how cutting carbohydrates affects blood sugar, insulin, organs, and overall metabolism. The researchers also considered whether the participants replaced carbohydrates primarily with fat, protein, or a mix.
What was studied? A meta-analysis published in “Clinical Nutrition” evaluated 149 randomized studies with a total of 9,104 adults from 28 countries.1 Researchers analyzed how carbohydrate-reduced diets–from moderate to very strict forms like the ketogenic diet–affect blood sugar, liver and kidney values, and overall metabolism. They also examined whether the missing carbohydrates were replaced by fat, protein, or a combination.
The role different diets play in metabolism and long-term health is also addressed by Nuno Alves in his book “Highway to Health – In 7 Steps to a Healthy Long Life,” set to be released on January 4, 2027.
Fewer Carbohydrates Led to Better Liver and Kidney Values
Results: Regardless of calorie content, all low-carb diets showed significant health improvements:
- Liver and kidney values improved, mainly with less extreme diet forms.
- Blood sugar and long-term blood sugar levels (HbA1c) decreased measurably.
- Insulin levels improved–the body used the hormone that moves sugar from the blood into cells more efficiently.
- The body increasingly shifted to fat burning, indicated by higher levels of so-called ketone bodies–substances that form when fat is used for energy instead of sugar.
- The hormone level of leptin, linked to hunger and body fat, decreased–a possible sign of better fat regulation.
- People with overweight, type 2 diabetes, or women particularly benefited from the dietary change.
- The best results were seen when participants replaced carbohydrates with a balanced mix of fat and protein.
Important: Very strict diets like the ketogenic diet sometimes increased liver values, which may indicate metabolic stress.
Significance: Carbohydrate-reduced diets can significantly improve sugar and fat metabolism. People with overweight, insulin issues, or diabetes could benefit greatly. Important: Implementation with medical or nutritional guidance is recommended–especially for extremely low-carb forms. Note that not all health factors (such as blood pressure or exercise) were considered in the analysis. Additionally, the results come from studies of varying quality, so they should be interpreted cautiously.
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