Spain Study: Keto-Mediterranean Diet Cuts Insulin Resistance 52%

Spain Study: Keto-Mediterranean Diet Cuts Insulin Resistance by Over Half

A study from Spain has found that a structured hybrid diet combining ketogenic and Mediterranean eating principles produced dramatic improvements in insulin resistance, blood fats, and body weight — all without serious side effects — over just 14 weeks of real-world clinical practice.

What Researchers Did

Scientists at the Food & Health Lab, Institute of Materials Science, University of Valencia tested what they call the Adaptive Ketogenic-Mediterranean Protocol (AKMP) on 112 overweight or obese adults. Of those, 105 completed the full program: 12 weeks of strict nutritional ketosis (no more than 20 grams of carbohydrates per day — roughly the amount in one small apple) followed by 2 weeks of gradual carbohydrate reintroduction. Participants had blood work, hormone panels, kidney and liver function tests, and body composition scans performed before and after the protocol.

What They Found

The results were striking across nearly every metabolic marker measured:

• Insulin resistance (HOMA-IR) dropped 52.8% — one of the most clinically meaningful changes in the study
• Fasting blood sugar fell by 13.7 mg/dL (already reported in US units), moving many participants meaningfully closer to normal ranges
• Triglycerides fell 35.1%, and the triglyceride-to-HDL ratio — a key marker of cardiovascular risk — dropped significantly
• Remnant cholesterol (RC), a newer but important cardiovascular risk marker, dropped 35.1% (10.64 mg/dL)
• LDL cholesterol fell 11.2%, while HDL (the protective cholesterol) remained stable
• Body weight dropped an average of 32.7 lbs (14.85 kg), or about 14.7% of starting weight
• Trunk fat — the dangerous abdominal fat — decreased by 22.2%
• Liver enzyme GGT dropped 47%, kidney filtration improved 11%, and the inflammatory marker CRP fell 24.6%

Safety Profile

Importantly, no serious adverse events were reported. Liver and kidney markers actually improved over the course of the study — a reassuring finding for patients and clinicians who may be cautious about ketogenic approaches.

Why This Matters for US Patients

In the United States, the American Diabetes Association (ADA) acknowledges low-carbohydrate and very low-carbohydrate diets as viable options for blood sugar management, but many American patients and even their doctors remain uncertain about safety and real-world feasibility. This Spanish real-world clinical trial — not a tightly controlled lab study — is significant because it reflects what happens in actual medical practice with diverse patients.

The degree of insulin resistance improvement (52.8% reduction in HOMA-IR) is especially relevant for the estimated 96 million American adults with prediabetes, many of whom are told to simply "watch their diet" without a specific, structured plan. The AKMP's hybrid approach — strict keto followed by gradual reintroduction — may also be more sustainable than indefinite strict low-carb eating, addressing one of the most common concerns US patients raise.

Remnant cholesterol, which this study tracked closely, is gaining attention in US cardiology as a risk factor that standard cholesterol panels can miss — making this research particularly timely for American patients managing both diabetes and heart disease risk.

Researchers appropriately caution that randomized controlled trials are still needed to confirm causality and long-term results.

Original Study

García-Gorrita, San Onofre, & Merino-Torres. "Adaptive Ketogenic-Mediterranean Protocol (AKMP) in Real Clinical Practice: 14-Week Pre-Post Cohort Study on Glucolipid Markers and Safety." Nutrients, 2025. DOI: 10.3390/nu17223559 | PMID: 41305609