Today, the research we’ll be highlighting builds on the Mediterranean diet, by adding some extra interventions. We’ve written before about the Mediterranean diet, here:

The Mediterranean Diet: What Is It Good For? ← What isn’t it good for?

The Mediterranean diet’s strengths come from various factors including its good plant:animal ratio (leaning heavily on the plants), colorful fruit and veg minimally processed, and the fact that olive oil is the main source of fat:

All About Olive Oil ← pretty much one of the healthiest fats we can consume, if not healthiest all-rounder fat.

This is not the first time we’ve talked about making the Mediterranean even better; see: Four Ways To Upgrade The Mediterranean Diet ← to make it even more anti-inflammatory, even more gut-healthy, even more heart-healthy, and even more brain-healthy, respectively.

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Researchers (Dr. Dolores Corella et al.) wanted to know the effectiveness of adding further interventions on top of the already-healthy Mediterranean diet.

Specifically, the Mediterranean diet, plus:

• Caloric restriction (600 fewer calories per day)
• Moderate exercise (brisk walking, strength, balance)
• Professional weight-loss support

On which note, the study participants were 4,746 adults (ages 55–75) categorized as overweight or obese, with metabolic syndrome but no diabetes at baseline, followed for six years.

With this in mind, the method may not be applicable to all people—if you are already exercising moderately, do not have extra weight to healthily lose, and are eating maintenance calories only, then cutting your caloric intake drastically will probably not be healthy or sustainable.

For more on the science of caloric restriction (including the pros and cons), see: Is Cutting Calories The Key To Healthy Long Life?

As for the study, the intervention group (Mediterranean diet plus those three things) and the control group (Mediterranean diet only) saw the following results after 6 years:

• Intervention group lost 3.3kg (7¼ lbs); control group lost 0.6kg (1⅓ lbs)
• Intervention group lost 3.6cm (1½ inches) waist circumference; control group lost 0.3cm (⅛ inch)
• Intervention group had 9.5% absolute risk of diabetes; control group had 12% risk

The overall reduction of diabetes incidence, however, was 31% lower for the intervention group than the control group

You may be wondering: since 9.5 is about 21% (not 31%) of 12, where did the 31% figure come from?

And the answer is: this is one of those places where absolute risk reduction, relative risk reduction, and hazard ratio-based incidence reduction get easily mixed up:

• Absolute risk reduction (ARR) = we take the cumulative risk in control and subtract the cumulative risk in intervention, so here, that’s 12.0% – 9.5% = 2.5 percentage points ARR
• Relative risk reduction (RRR) = we take the ARR we just calculated, and subtract the cumulative risk in control, so here, that’s 2.5/12 = 20.8% RRR
• Hazard ratio-based incidence reduction = what happens if we apply the resultant hazard ratio to person-years, i.e. instead of of looking at just those 6 years (and not caring if someone gets diabetes in 7 years, say), we take each participant’s 6 years and stretch them all end-to-end, so that we can see more accurately what incidence rate will be over more time. We then take the number of person-years generated (in this case, 6 years x 4746 people = 28,476 person-years, which is a lot of data), look at the reduction rate, and then scale it back down (keeping the same ratio) to a number that makes for a clearer representation that’s easy to apply to other models, in this case, 1,000 person years, using the same hazard ratio as we found from the 28,476 person-years. The result of this calculation, in this case, is a 31% lower incidence rate. This is more or less what we might reasonably have expected from a glance at the data—we could expect that it would be higher than the RRR, because this time we get to factor into the equation the people who will get diabetes in year 7, year 8, year 9, etc, from only a 6-year study, because of how we laid everyone’s 6 years end-to-end.

You can find the paper itself, here: Comparison of an Energy-Reduced Mediterranean Diet and Physical Activity Versus an Ad Libitum Mediterranean Diet in the Prevention of Type 2 Diabetes

Is it worth it?

If you have those 7¼ lbs and 1½ inches to lose, then a 31% reduction in diabetes risk is a big benefit.

If, on the other hand, you don’t, then as we say, probably skipping 600kcal per day is not so good an idea for you.

For everyone, meanwhile, moderate exercise is of course great.

As for the professional weight loss help? Well, that depends on the nature of the help, and this study didn’t separate its effects (if any) from the effects of the caloric reduction and moderate exercise. So, honestly we think it’s unhelpful that they included it with doing a separate control for it.

Want to reduce diabetes risk without reducing calories?

Check out:

How To Prevent And Reverse Type 2 Diabetes: Turn Back The Clock On Insulin Resistance!

Take care!