Moderate Postmeal Walking Has No Beneficial Effects Over Resting on Postprandial Lipemia, Glycemia, Insulinemia, and Selected Oxidative and Inflammatory Parameters in Older Adults with a Cardiovascular Disease Risk Phenotype: A Randomized Crossover Trial, The Journal of Nutrition, 18 July 2019
This study looked at four conditions: a Western Diet meal with and without a 30-minute walk afterwards (WD-W, WD-R), and a Mediterranean Diet meal with and without a walk (MD-W, MD-R).
Conclusions: In older adults with an increased CVD risk, the MD was associated with superior effects on several postprandial parameters (e.g., triglycerides), in comparison to the WD. Data revealed no relevant differences regarding the effects of postmeal walking and resting.
The Mediterranean diet actually wasn’t that superior. It resulted in lower triglycerides than the Western diet but it increased glucose:
Plasma glucose was higher after the MD than after the WD, as was serum insulin.
Both meals were high in fat though, so any carb is going to have a tough time being cleared, and the MD had more carb. It doesn’t mean carbs are bad, it means it’s not a good idea to eat them with a lot of fat. The traditional Mediterranean diet, as I discovered, was low in fat. Dietary fat contributes to insulin resistance which leads to high blood glucose.
If they had tested a low-fat version of the MD, they may have found lower triglycerides:
Previous intervention studies have shown that the ingestion of a high-fat meal induces a pronounced and sustained increase in serum triglycerides and that the postprandial lipemic response is directly proportional to the amount of fat ingested.
In the end:
On the basis of the present data, in older adults with a CVD risk phenotype, none of our 4 treatments (WD-W, WD-R, MD-W, MD-R) can be rated as superior regarding their acute effects on the measured postprandial metabolic, oxidative, and inflammatory parameters.
This isn’t going to make news because it shows the Mediterranean diet — the industry-promoted Mediterranean diet — as ineffectual.
These were big meals, over 1000 calories each, and as I said, high in fat. The Western Diet was 53% fat, the Mediterranean Diet was 36% fat. A low-fat diet is about 15% fat. The Okinawans and Cubans ate less than that.
What drew my interest was the walking aspect of this study. I thought that walking after eating would lower blood glucose but it didn’t:
Significantly higher plasma glucose concentrations were found directly after walking (1.5 h postprandial) for both meal types.
This was a surprise. But it makes me happy. I like to walk, but it’s the last thing I want to do after a big meal.