Keto vs Mediterranean diet compared: what the Keto-Med crossover trial and the two-year DIRECT trial found for weight, blood sugar and cholesterol, and what people weigh up.
Fact-checked against FDA labels and official sources; not yet reviewed by a licensed clinician. This page is education, not medical advice. Talk to your doctor before starting, stopping or changing any treatment.
Key takeaways
- In the Keto-Med crossover trial, HbA1c fell 9% on keto and 7% on a Mediterranean-plus diet after 12 weeks, a difference that was not statistically significant.[1]
- Keto lowered triglycerides more (-16% vs -5%) but LDL cholesterol rose on keto (+10%) and fell on the Mediterranean-plus diet (-5%).[1]
- Over two years in DIRECT, weight loss was similar on low-carbohydrate (4.7 kg) and Mediterranean (4.4 kg) diets, and both beat low-fat (2.9 kg).[2]
- In PREDIMED, a Mediterranean diet with olive oil or nuts lowered major cardiovascular events compared with a reduced-fat diet (HR 0.69 and 0.72).[4]
In short: When Stanford researchers had the same 40 adults follow a keto diet and a Mediterranean-style diet for 12 weeks each, weight loss was close (about 8% vs 7%) and blood sugar (HbA1c) improved about the same on both. Keto lowered triglycerides more but raised LDL (“bad”) cholesterol, while LDL went down on the Mediterranean diet, which also supplied more fiber and was easier to keep up afterward. In a separate two-year trial, low-carb and Mediterranean diets also led to similar weight loss.
This page puts the two eating patterns side by side using the trials that compared them directly, with the numbers each one reported. It does not crown a winner, because the trials did not find a clear one for weight. For the full background on each pattern, see our guides to the keto diet and the Mediterranean diet; for every diet ranked by long-term evidence, see the 10 best diets for weight loss. This is general education, not a personal plan. If you take medicines for diabetes or blood pressure, talk with your clinician before a big change in what you eat, because doses sometimes need adjusting.
The two diets in one minute
| Keto (well-formulated ketogenic diet) | Mediterranean diet | |
|---|---|---|
| The core idea | Cut carbohydrates so low that the body burns more fat and makes ketones | Eat mostly plants, whole grains, legumes, fish and olive oil, with little red meat or sweets |
| Carbohydrates | About 20 to 50 grams a day in the Keto-Med trial; research usually defines it as no more than 50 grams a day | No set limit; carbs come mainly from vegetables, fruit, legumes and whole grains |
| Foods it leaves out | Grains, legumes, most fruit, sugars and starchy vegetables | Few: it limits added sugar, refined grains, processed and red meat |
| Main fats | A large share of calories from fat (meat, fish, eggs, cheese, nuts, oils) | Mostly extra-virgin olive oil and nuts |
| Calorie counting | Not required; appetite often drops when carbs are very low | Not required in PREDIMED; DIRECT used a calorie-limited version for weight loss |
| Best-known strength in trials | Lower triglycerides and blood sugar, especially early | Fewer heart attacks and strokes in PREDIMED; more fiber; easier to keep up |
Notice what they share. In the Keto-Med trial, both diets were built around plenty of non-starchy vegetables and both cut out added sugars and refined grains. The difference was three food groups: the Mediterranean version kept legumes, fruit and whole, intact grains, and keto removed them. That design makes this trial useful, because it isolates the question most people actually ask: do those three food groups help or hurt?
The head-to-head trial: Keto-Med (2022)
The Keto-Med trial, led by Christopher Gardner at Stanford and published in the American Journal of Clinical Nutrition in 2022, enrolled 40 adults with prediabetes or type 2 diabetes. It was a crossover trial: each person followed both diets for 12 weeks, in random order, so every participant was compared with themselves. For the first 4 weeks of each phase, meals were delivered; for the next 8 weeks, people shopped and cooked on their own. After both phases, researchers checked in again 12 weeks later, when people could eat however they liked. The main analysis included the 33 people with complete data.
| Item | Keto | Mediterranean-plus |
|---|---|---|
| Weight loss | 8% | 7% |
| HbA1c drop | 9% | 7% |
| Triglyceride drop | 16% | 5% |
| HDL rise | 11% | 7% |
Mean percent changes from baseline in 33 adults with prediabetes or type 2 diabetes. The HbA1c and weight differences were not statistically significant.
Source: Gardner CD et al., American Journal of Clinical Nutrition 2022 (Keto-Med trial) (checked on October 6, 2026)
Here is what the trial reported:
- Blood sugar (the main question). HbA1c, a measure of average blood sugar over about three months, fell 9% on keto and 7% on the Mediterranean-plus diet. The difference was not statistically significant. Both diets improved it from where people started.
- Weight. Weight fell about 8% on keto and 7% on the Mediterranean-plus diet. The authors flagged an “order effect”: results depended partly on which diet came first, so they did not treat this as a clear difference.
- Triglycerides. These dropped 16% on keto and 5% on the Mediterranean-plus diet, a significant difference in keto’s favor.
- LDL cholesterol. LDL rose 10% on keto and fell 5% on the Mediterranean-plus diet, a significant difference in the other direction. The authors called this a “potential untoward risk”.
- Nutrients. On keto, people took in less fiber and less of three nutrients than on the Mediterranean-plus diet. During the self-shopping weeks, the Mediterranean version supplied more fiber, vitamin C, folate and magnesium.
- Staying with it. At the 12-week follow-up, people’s eating looked more like the Mediterranean-plus diet than keto, which the authors read as a sign it may be easier to sustain.
| Item | Value |
|---|---|
| Keto (LDL up) | 10% |
| Mediterranean-plus (LDL down) | 5% |
Mean percent change in LDL cholesterol from baseline: +10% on keto, -5% on the Mediterranean-plus diet (P = 0.01).
Source: Gardner CD et al., American Journal of Clinical Nutrition 2022 (Keto-Med trial) (checked on October 6, 2026)
Keep the limits in mind. Forty people for 12 weeks per diet is a small, short trial, all participants had prediabetes or type 2 diabetes, and part of the study ran during the COVID-19 shutdowns, when some weights were self-reported. It is a good look at how the two diets differ in the same bodies, not proof of what happens over years.
What longer trials add
For weight over a longer stretch, the best direct comparison is the DIRECT trial, published in the New England Journal of Medicine in 2008. It assigned 322 adults with moderate obesity (mean age 52, 86% men) to a low-fat diet, a calorie-limited Mediterranean diet or a low-carbohydrate diet for two years. The low-carb diet in DIRECT was not strict keto, but it was the closest arm.
Both the low-carb and Mediterranean groups lost more than the low-fat group, and they were close to each other: 4.7 kg (about 10 lb) and 4.4 kg (about 10 lb). Each had a different extra: cholesterol ratios improved most on low-carb, while blood sugar and insulin improved most on the Mediterranean diet among the 36 people with diabetes. The authors concluded that personal preference and metabolic needs could guide the choice.
The wider evidence
- -0.91 kgextra weight lost on very-low-carb keto diets than on low-fat diets after 12+ months (13 trials)Bueno et al., Br J Nutr 2013
- 0.69hazard ratio for heart attack, stroke or heart death with a Mediterranean diet plus olive oil vs a reduced-fat diet (7,447 adults)PREDIMED, NEJM 2018
- 609adults in DIETFITS, where healthy low-carb and healthy low-fat diets gave similar 12-month weight lossGardner et al., JAMA 2018
Checked on October 6, 2026
A meta-analysis of 13 trials lasting a year or more found that very-low-carbohydrate ketogenic diets (no more than 50 grams of carbs a day) led to slightly more weight loss than low-fat diets, by 0.91 kg (about 2 lb), along with lower triglycerides and higher HDL and LDL cholesterol. That LDL pattern matches Keto-Med.
The Mediterranean diet’s strongest evidence is about the heart, not weight. In PREDIMED, 7,447 adults aged 55 to 80 at high cardiovascular risk followed a Mediterranean diet with extra-virgin olive oil or nuts, or a reduced-fat diet. Major cardiovascular events were lower in both Mediterranean groups (hazard ratios 0.69 and 0.72). The trial was republished in 2018 after problems with how some participants were randomized; the results held. PREDIMED did not ask people to cut calories, and weight barely changed in any group, which is a reminder that the Mediterranean diet works for weight loss mainly when portions or calories are also managed, as in DIRECT.
Side by side: what each diet does well
| Question | Keto | Mediterranean | Source |
|---|---|---|---|
| Weight loss over 12 weeks | About 8% | About 7% | Keto-Med 2022 (difference unclear because of an order effect) |
| Weight loss over 2 years | 4.7 kg (low-carb arm) | 4.4 kg | DIRECT 2008 |
| Average blood sugar (HbA1c) | -9% | -7% | Keto-Med 2022 (not significantly different) |
| Triglycerides | -16% | -5% | Keto-Med 2022 |
| LDL cholesterol | +10% | -5% | Keto-Med 2022 |
| Fiber | Lower | Higher | Keto-Med 2022; DIRECT 2008 |
| Heart attacks and strokes | Not tested in a large outcome trial | Fewer in PREDIMED (HR 0.69 to 0.72) | PREDIMED 2018 |
| Easier to keep up afterward | Less so in Keto-Med follow-up | More so in Keto-Med follow-up | Keto-Med 2022 |
Why the weight results are so close
Both diets cut out the same easy sources of extra calories: sugary drinks, sweets, white bread and pastries. Most people who switch to either one end up eating less overall, which is what drives weight loss on any diet, as our guide to the calorie deficit explains. Over months, adherence matters more than the macronutrient split: large trials such as DIETFITS found similar results for healthy low-carb and healthy low-fat diets when people stuck with them.
That is why the most useful question is not “which diet burns more fat” but “which one can I live with?” A diet you keep for two years will beat a “better” diet you drop after two months. Both patterns can be high in protein, which helps with fullness and protecting muscle; see our high-protein diet guide and the most filling foods for ideas that fit either one.
What a day looks like on each
| Meal | Keto example | Mediterranean example |
|---|---|---|
| Breakfast | Eggs scrambled with spinach and feta | Plain Greek yogurt with berries, walnuts and oats |
| Lunch | Big salad with salmon, avocado and olive oil dressing | Lentil and vegetable soup with a slice of whole-grain bread |
| Snack | A handful of almonds or cheese with cucumber | An apple with a handful of almonds |
| Dinner | Roast chicken thighs with broccoli and cauliflower mash | Grilled fish with chickpeas, roasted vegetables and olive oil |
These are illustrations, not a meal plan. Our macro calculator shows how your calories split into protein, carbs and fat on different patterns, and the calorie calculator gives a starting estimate of your daily needs.
Who might lean one way or the other
There is no single right answer, but the trials point to some honest trade-offs people weigh with their clinician or a registered dietitian:
- High triglycerides or blood sugar. Keto lowered triglycerides more in Keto-Med and in the 13-trial meta-analysis, and lowered glucose on continuous monitors more. Both diets improved HbA1c. If you have type 2 diabetes or insulin resistance, either may help, and medicines may need adjusting before you start.
- High LDL cholesterol or heart disease. LDL rose on keto in Keto-Med and in the meta-analysis. The Mediterranean diet has the outcome trial (PREDIMED) showing fewer heart attacks and strokes. People with high LDL often check their lipids if they try keto.
- Fiber, gut comfort and variety. The Mediterranean diet keeps beans, fruit and whole grains, so it supplies more fiber. Keto can be lower in fiber and several vitamins and minerals unless it is planned carefully.
- Liking structure. Some people find a clear rule (“almost no carbs”) easier than portion judgment. Others find keto’s long list of off-limits foods hard in family meals, travel or restaurants.
- Medicines and conditions that need care. Keto needs medical supervision for people taking insulin, sulfonylureas or SGLT2 inhibitors, and for people with pancreatitis, advanced liver or kidney disease, gallbladder disease or familial high cholesterol, and during pregnancy. Our keto guide lists these in full.
Trying either diet sensibly
- Check your starting numbersAsk for a lipid panel and HbA1c if you have diabetes, prediabetes or high cholesterol.
- Talk about your medicinesBlood sugar and blood pressure medicines may need adjusting, especially on keto.
- Keep the shared coreLots of non-starchy vegetables, no sugary drinks, fewer refined grains on both diets.
- Give it 12 weeksTrack weight, waist and how you feel; recheck labs with your clinician.
- Plan the long termChoose the version you could still follow in a year.
A middle path many people use
The two diets are not all-or-nothing. Keto-Med’s Mediterranean-plus diet was itself lower in carbohydrate than a typical American diet, because it dropped added sugars and refined grains. Many people end up near that middle: Mediterranean foods, with fewer starches and sweets. It keeps the olive oil, nuts, fish, beans and vegetables linked to heart health in PREDIMED. Compare other patterns in our diets hub or read about the DASH diet. If you also want to change when you eat, see intermittent fasting vs calorie counting, and for the habits that keep weight off after any diet, see maintaining weight loss.
If you are taking a GLP-1 medicine, eating less overall becomes easier, and protein and fiber become more important for muscle and digestion. Our GLP-1 diet guide explains how either pattern can be adapted. More comparisons are in the compare hub.
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- Do my cholesterol or triglyceride numbers make one of these diets a better fit?
- Do any of my medicines need adjusting before I cut carbohydrates?
- Should I recheck my lipids and HbA1c after 12 weeks?
- Would a registered dietitian help me plan either diet with enough fiber and nutrients?
Frequently asked questions
Is keto or Mediterranean better for weight loss?
Trials found them close. In Keto-Med, weight fell about 8% on keto and 7% on a Mediterranean-plus diet over 12 weeks; over two years in DIRECT, low-carb and Mediterranean groups lost 4.7 and 4.4 kg. The one you can keep up matters most.
Does keto raise cholesterol?
LDL cholesterol rose 10% on keto in Keto-Med, and a 13-trial meta-analysis also found higher LDL on very-low-carb diets than on low-fat diets. Triglycerides fell and HDL rose. People with high LDL often check their lipids with a clinician.
Which diet is better for type 2 diabetes?
In Keto-Med, both diets improved HbA1c (-9% and -7%) with no significant difference. Diabetes medicines, especially insulin and sulfonylureas, may need adjusting before a low-carb diet, so plan it with your care team.
Can you combine keto and Mediterranean?
Some people eat a lower-carb Mediterranean pattern: olive oil, fish, vegetables and nuts, with fewer starches and no added sugar. Keto-Med's Mediterranean-plus diet already cut added sugars and refined grains.
Why was the Mediterranean diet easier to stick to?
It keeps more foods, including fruit, beans and whole grains. At the 12-week follow-up in Keto-Med, people's eating was closer to the Mediterranean-plus diet than to keto.
References
- Gardner CD, Landry MJ, Perelman D, et al.. Effect of a ketogenic diet versus Mediterranean diet on glycated hemoglobin in individuals with prediabetes and type 2 diabetes mellitus: The interventional Keto-Med randomized crossover trial. American Journal of Clinical Nutrition, 2022. doi:10.1093/ajcn/nqac154 · PMID 35641199 · NCT03810378 (accessed October 6, 2026) Randomized trial
- Shai I, Schwarzfuchs D, Henkin Y, et al.. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet (DIRECT). New England Journal of Medicine, 2008. doi:10.1056/NEJMoa0708681 · PMID 18635428 · NCT00160108 (accessed October 7, 2026) Randomized trial
- Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition, 2013. doi:10.1017/S0007114513000548 · PMID 23651522 (accessed October 7, 2026) Meta-analysis
- Estruch R, Ros E, Salas-Salvadó J, et al.. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts (PREDIMED, republished). New England Journal of Medicine, 2018. doi:10.1056/NEJMoa1800389 · PMID 29897866 (accessed October 6, 2026) Randomized trial
- Estruch R, Martínez-González MA, Corella D, et al.. Effect of a high-fat Mediterranean diet on bodyweight and waist circumference: a prespecified secondary outcomes analysis of the PREDIMED randomised controlled trial. The Lancet Diabetes & Endocrinology, 2019. doi:10.1016/S2213-8587(19)30074-9 · PMID 31003626 (accessed October 6, 2026) Randomized trial
- Dyńka D, Rodzeń Ł, Rodzeń M, et al.. The ketogenic diet is not for everyone: contraindications, side effects, and drug interactions. Annals of Medicine, 2026. doi:10.1080/07853890.2025.2603016 · PMID 41486865 (accessed October 7, 2026) Review
- JARDIANCE (empagliflozin) prescribing information, section 5.1 Ketoacidosis. U.S. Food and Drug Administration, 2023. (accessed October 6, 2026) Drug label
- Gardner CD, Trepanowski JF, Del Gobbo LC, et al.. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults (DIETFITS randomized clinical trial). JAMA, 2018. doi:10.1001/jama.2018.0245 · PMID 29466592 · NCT01826591 (accessed October 7, 2026) Randomized trial
Facts checked on October 6, 2026
Educational information, not medical advice. Talk with a qualified healthcare professional about your own situation. In an emergency call 911.