Mediterranean diet trials separate weight loss from fat loss

Fat proportions, diet comparisons and long-term outcomes answer different questions

The body-composition report also found a greater increase in lean mass as a proportion of body weight in the intervention group. Differences in change were 0.88 percentage points after a year and 0.34 percentage points after 3 years. Lean mass refers to components other than fat, rather than muscle alone. A higher proportion of lean mass does not establish an increase in the absolute amount of muscle.[1]

The 95% confidence intervals for those lean-mass proportion differences were 0.63–1.12 percentage points at a year and 0.09–0.60 percentage points at 3 years. The authors concluded that the intervention reduced fat and attenuated age-related loss of lean mass.[1]

The differences were smaller at 3 years than at a year, for both fat proportion and visceral fat. Statistically significant differences from the control group remained at 3 years, but the early advantage did not stay the same size. This gives a more useful perspective than projecting the first year’s change indefinitely into the future. The question of what remains over time is separate from the question of what changes early. This time scale is also useful when you step onto the bathroom scale in the morning hoping to see a short-term change: the trial distinguishes the early result from the advantage that was still present years later.[1]

The analysis also has limits. It did not measure body composition in the entire trial population. It concerned a subgroup from centers with access to DXA equipment. The main analysis included participants who completed follow-up, while sensitivity analyses also addressed missing data. A sensitivity analysis checks how results behave when analytical assumptions or methods change. These procedures matter when interpreting findings from a selected measurement subgroup.[1]

To ask whether the dietary pattern itself has a special advantage, it helps to compare diets that both restrict energy. A randomized trial in 144 postmenopausal women with abdominal obesity compared a Mediterranean diet with a Central European diet that was moderate in carbohydrates and high in dietary fiber. The intervention lasted 16 weeks. Across the trial, body weight fell by 8.8%, waist circumference by 7.0% and visceral fat by 24.6%, with no difference between groups.[12]

Both diets restricted energy, and average changes in weight, waist and visceral fat were similar. Total cholesterol, triglycerides, glucose and blood pressure showed a similar pattern. A diet can be part of a successful program without outperforming another energy-restricted eating pattern in the comparison that was actually tested.[12]

Within each diet group, women who followed the prescribed diet more closely lost more weight. When researchers separated participants by adherence, a significant visceral fat reduction appeared only among women who adhered more closely to the Central European diet. Visceral fat reduction was also associated with an increase in the proportion of dietary fiber. That adherence-based analysis answers a narrower question than the overall comparison between randomized diet groups.[12]

Conditions that help people sustain dietary change were also examined in a longitudinal analysis of 2,985 PREDIMED-Plus intervention participants. People with greater confidence at baseline in their ability to change their diet, known as self-efficacy, and those with higher initial fiber intake were more likely to make successful changes at both 6 and 12 months. Having more than 3 chronic conditions or depression was associated with less successful change.[13]

These are associations with factors present at the start, rather than evidence that simply telling someone to be more confident causes dietary success. The authors called for tailored interventions for participants with multiple chronic conditions or depression. Difficulty following a meal plan should therefore prompt attention to the conditions in which a person is trying to change, rather than an assumption that the food pattern alone resolves the problem.[13]

DIRECT-PLUS offers another view of visceral fat. This trial followed 294 participants for 18 months, comparing healthy dietary guidelines, a Mediterranean diet and a version enriched in plant polyphenols and lower in red and processed meat. Polyphenols are a group of compounds found in plants. All groups combined their dietary approach with physical activity. Participants had a mean age of 51, and 88% were men.[18]

MRI-measured visceral fat fell by 4.2% in the healthy-guidelines group, 6.0% in the standard Mediterranean group and 14.1% in the enriched Mediterranean group. Both Mediterranean groups received walnuts. The enriched version also included green tea, a separate shake made from an aquatic plant, and less red meat. The comparison involved several food changes together with activity, so its results cannot be assigned to a single ingredient.[18]

Weight loss was 2.7% in the standard Mediterranean group and 3.9% in the enriched group. The enriched group lost more than twice as much visceral fat as the standard group, while their weight-loss percentages differed far less. This illustrates why the scale cannot describe all changes inside the body. Mean body mass index was 31.2, participant retention was 89.8%, and 79.3% completed MRI measurements suitable for analysis. Visceral fat differences remained after accounting for age, sex, waist circumference and weight loss.[18]

Longer-term health outcomes add another question. A prespecified secondary analysis of PREDIMED-Plus included 4,746 participants with overweight or obesity and metabolic syndrome who did not have diabetes. Absolute diabetes risk over 6 years was 12.0% in the control group and 9.5% in the intervention group. An analysis accounting for time to diagnosis found a 31% relative reduction in incidence, with a confidence interval of an 18–41% reduction.[11]

There were 349 diabetes cases in the control group and 280 in the intervention group. Reading the relative reduction alongside the absolute risks gives a clearer sense of the finding’s size. The program planned an energy reduction of 600 kcal per day and added physical activity and behavioral support. Dietary adherence was self-reported, and diabetes incidence was a prespecified secondary outcome. Participants were aged 55–75 and had neither cardiovascular disease nor diabetes at baseline.[11]

Common misconceptions

“Olive oil and nuts contain fat, so a Mediterranean diet must cause weight gain.” The unrestricted-diet trial does not support that claim. The diets high in plant fats did not produce a significant weight difference compared with advice to reduce dietary fat. The finding concerns a whole dietary pattern. It does not demonstrate that adding oil or nuts to otherwise unchanged meals causes weight loss.[17]

“A Mediterranean diet means I can ignore how much I eat and still lose a lot of weight.” The clearer weight-loss result came from PREDIMED-Plus, which included energy reduction, physical activity and behavioral support. In the postmenopausal women’s trial, the Mediterranean diet had no overall advantage over another diet when both restricted energy. Removing those conditions leaves a claim different from the research.[2][12]

“Less visceral fat means more muscle.” Fat and lean mass, and their amounts and proportions, are separate outcomes. An improvement in lean mass as a share of body weight is not a direct measure of strength or movement ability. The DXA analysis assessed body composition. Strength and physical function require their own measurements, so neither should be claimed from these figures.[1]

Finally, several papers are not necessarily several independent trials. The PREDIMED-Plus reports on weight, adherence, body composition and diabetes examine different participants, time points or outcomes within the same large trial. They provide different windows onto the intervention. Counting each publication as a separate success would exaggerate how often the whole program has been independently tested.[1][2][4][11]

What you can do today

• If you are adopting a Mediterranean diet for weight loss, review the amounts across your usual meals and reorganize them to reduce energy intake, rather than just adding oil or nuts. The weight-loss trial combined dietary changes with physical activity and support.[2] The longer-term study planned a reduction of 600 kcal per day with support for a specific population; that amount is a study condition to discuss with your doctor.[11]
• On the day you change your meals, also make time for physical activity and carry it out. PREDIMED-Plus promoted physical activity alongside dietary change.[2]
• If you often eat red or processed meat, revise your meals to include less of it and more plant-based foods. The enriched Mediterranean diet tested in DIRECT-PLUS combined these changes with other food choices and physical activity.[18]
• If low confidence, chronic conditions or depression make dietary change difficult, seek support adapted to your circumstances. Starting confidence and health circumstances were associated with success in changing diet, and the authors recommended tailored support for people facing these barriers.[13]
• Consult your doctor before making dietary changes related to disease or treatment.[11]

Connect Mediterranean meals with movement at On the Shore Tachikawa

Mediterranean diet research treats food changes and physical activity as parts of a shared routine. On the Shore Tachikawa offers a place to keep the movement habit going alongside changes at the dinner table.

The lava-stone hot yoga studio also offers room-temperature yoga. Pregnant guests cannot join lava-stone hot yoga; room-temperature maternity yoga is available. Guests told by a doctor not to exercise cannot join. Many of our yoga instructors speak English, and the studio’s owner often helps guests from the US bases in English herself.

A trial yoga lesson costs ¥1,980 including tax. The 60-minute lesson includes 2 bath towels, 1 face towel and yoga mat rental. Check prices and the trial booking page when planning your visit.

The studio is a 1-minute walk from the North Exit of JR Tachikawa Station, at 3F Etoile Bldg, 2-14-10 Akebonocho, Tachikawa, Tokyo. It is open every day 8:00–23:30. If you use the station for shopping or work, consider which times before or after those visits would fit your routine.

Alongside lava-stone hot yoga and room-temperature yoga, the studio offers Pilates, women-only kickboxercise, boxercise, HIIT and personal training, with 25+ kinds of yoga lessons. The studio information lets you compare activities to fit into daily life while reviewing your meals.

References

1. An Energy-Reduced Mediterranean Diet, Physical Activity, and Body Composition — J. Konieczna et al., 2023, JAMA Network Open. DOI: 10.1001/jamanetworkopen.2023.37994
2. Effect of a Lifestyle Intervention Program With Energy-Restricted Mediterranean Diet and Exercise on Weight Loss and Cardiovascular Risk Factors: One-Year Results of the PREDIMED-Plus Trial — J. Salas-Salvadó et al., 2018, Diabetes Care. DOI: 10.2337/dc18-0836
3. Effect of a Nutritional and Behavioral Intervention on Energy-Reduced Mediterranean Diet Adherence Among Patients With Metabolic Syndrome: Interim Analysis of the PREDIMED-Plus Randomized Clinical Trial. — C. Sayón-Orea et al., 2019, JAMA. DOI: 10.1001/jama.2019.14630
4. Comparison of an Energy-Reduced Mediterranean Diet and Physical Activity Versus an Ad Libitum Mediterranean Diet in the Prevention of Type 2 Diabetes : A Secondary Analysis of a Randomized Controlled Trial. — M. Ruiz-Canela et al., 2025, Annals of internal medicine. DOI: 10.7326/annals-25-00388
5. Weight loss and metabolic health effects from energy-restricted Mediterranean and Central-European diets in postmenopausal women: A randomized controlled trial — J. Bajerska et al., 2018, Scientific Reports. DOI: 10.1038/s41598-018-29495-3
6. Factors associated with successful dietary changes in an energy-reduced Mediterranean diet intervention: a longitudinal analysis in the PREDIMED-Plus trial — C. Fernandez-Lázaro et al., 2021, European Journal of Nutrition. DOI: 10.1007/s00394-021-02697-8
7. Effect of a high-fat Mediterranean diet on bodyweight and waist circumference: a prespecified secondary outcomes analysis of the PREDIMED randomised controlled trial. — R. Estruch et al., 2019, The lancet. Diabetes & endocrinology. DOI: 10.1016/s2213-8587(19)30074-9
8. The effect of high-polyphenol Mediterranean diet on visceral adiposity: the DIRECT PLUS randomized controlled trial — H. Zelicha et al., 2022, BMC Medicine. DOI: 10.1186/s12916-022-02525-8

Cover photo: Mediterranean-style salad with lettuce, tomatoes and red peppers, dressed with olive oil and salt. (Photo: Lablascovegmenu from London / CC BY 2.0 / Wikimedia Commons)

Information as of October 2026. For your own health, consult a doctor.

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