Mediterranean Diet and Body Composition Study Spotlight Take-Away with Chef Dr. Mike

by Michael S. Fenster, MD

“No diet will remove all the fat from your body because the brain is entirely fat. Without a brain, you might look good, but all you could do is run for public office.”
― George Bernard Shaw

The new year invariably brings an assortment of resolutions fueled by hucksters lighting the twin wicks of guilt and self-loathing after a holiday season with perhaps an indulgence or two too much. They cram our inboxes and screech at us from pop-ups and late-night adverts hurling dire warnings at us like epithets from a drunken sailor. Chief among these is the infamous and dreaded need for a “New Year, New You.” It is a mantra of the moribund, a phrase incessantly repeated by way too perky and slightly terrifying Shake Weight™ hustlers to launch a thousand miracle weight loss gimmicks, none of which actually work.

But none of that negates the fact that, in terms of health, body composition does matter. A combination of genetics, gut microbiome, aging, diet, and activity all impact the reflection in the mirror. Specific body types like those with excess visceral fat, or “belly fat,” do correlate to an increased risk of type II diabetes and cardiovascular disease. All of this raises the question: can lifestyle-based interventions like dietary choices and physical activity make a sustained difference? These questions are not trivial, given the fact that recent data has suggested that weight loss alone through mechanisms like bariatric surgery and drugs may not be enough to affect a sustained reversal or remission of type II diabetes and its complications.

Previous studies have examined the impact of a Mediterranean-style approach to diet and its impact on health-related outcomes. Those results have suggested a positive impact on reducing obesity and particularly visceral fat. The positive impact of increased physical activity on weight and health is well known. This particular study looked at the combined effect of the Mediterranean-style approach to diet (and also energy-restricted) and increased physical activity on these endpoints.

The Study:

      • The study examined 1,521 participants from the PREDIMED-Plus (Prevención con Dieta Mediterránea-Plus) cohort over a three-year period.

      • The cohort is drawn from 23 Spanish research centers, including men and women (52.1 percent men) 55 to 75 years old, with a mean age of 65.3.

      • The participants had a body mass index (BMI) between 27 and 40, as well as metabolic syndrome.

      • The patients were randomly selected for a multi-factorial intervention (energy-reduced Mediterranean diet with increased physical activity) or a control group (usual care with advice to follow an ad libitum Mediterranean diet with no physical activity recommendations).

    The Take-Away:

        • The endpoints included changes in total fat, lean mass, and visceral fat.

        • Clinical relevance was assessed as a 5 percent or more improvement from baseline.

        • The intervention arm experienced a greater reduction in the percentage of total fat and visceral fat.

        • The intervention arm experienced a greater increase in total lean mass.

      The Caveat:

      The endpoints of total body fat, visceral body fat, and lean body mass were assessed at baseline, at one year, and at the study completion (three years). Clinical relevance, i.e., meaningful fat reduction and increased muscle mass, were defined as a 5 percent change from baseline. This number was used because it is a historic cut-off point for studies examining weight loss strategies in terms of beneficial cardio-metabolic changes.

      Compared to their baseline, those in the intervention group were significantly more likely to experience a clinically relevant reduction in total fat (1,677 g, roughly 3.7 pounds) and a clinically relevant loss of visceral fat (154 g; 0.34 pounds or roughly 5.5 ounces). Despite the loss of lean mass in the intervention group as a result of the weight-loss process, the ratio of lean mass to fat mass increased over follow-up in the intervention group and remained unchanged in the control group.

      However – and this is a critical point – by year three, the magnitude of these changes in the intervention group had waned considerably. For example, by year three, the amount of weight loss compared to baseline was roughly 1,022 g (roughly 2.2 pounds). For visceral fat, at year three, there was only a 72 g (or 2.5 ounces – the weight of one jumbo egg) loss from baseline. While statistically significant, these are small changes.

      To put this in perspective, in the intervention arm at year one (versus baseline) those in the intervention arm lost 1.14 percent of total fat mass, which faded to a little over half a percent by year three. By year three, those in the control group remained fairly constant, experiencing a 0.14 percent loss of total fat. The findings with respect to the percentage of visceral fat mass are even less impressive. By year three, those in the intervention arm had only sustained a 0.03 percent loss. Those in the control group experienced a 0.01 percent gain. In other words, by year three – in terms of the percentage of visceral fat mass lost – it was a statistical wash.

      In looking at the success rate for each variable, the numbers for the intervention remain unimpressive, especially examining year three compared to baseline. For example, in terms of the percentage of total fat mass lost that year three 126 out of 543 (23 percent) in the intervention group experienced at least a 5 percent (and thus clinically relevant) improvement. However, in the control group, 17 percent (100 out of 590) also experienced a clinically relevant improvement. In terms of visceral fat mass loss, 45 percent (236 out of 522) of the intervention arm achieved a clinically meaningful improvement. However, so did 38 percent (214 out of 569) of the controls.

      When examining such studies, it is always critical to understand and remember the endgame. Here, ultimately, the goal is to reduce the incidence and prevalence of type II diabetes and its complications. Are these changes, in terms of the intervention group versus the control, statistically significant; a change in the percentage and absolute total fat mass, lean mass, and the total lean mass to total fat mass ratio, as well as an absolute reduction of the visceral fat mass? Yes. Are those changes clinically meaningful in terms of achieving the endgame? That remains unknown.

      The Mediterranean-style dietary approach, when executed in terms of eating more fresh and wholesome foods, is something that is both economical and practical to embrace. That action, in fact, was the control group in this study. And that, no matter the intervention, is a great place to start!

      The Study:

      Konieczna J, Ruiz-Canela M, Galmes-Panades AM, et al. An Energy-Reduced Mediterranean Diet, Physical Activity, and Body Composition: An Interim Subgroup Analysis of the PREDIMED-Plus Randomized Clinical Trial. JAMA Netw Open. 2023;6(10):e2337994. doi:10.1001/jamanetworkopen.2023.37994

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