Studying aging in humans 2 - practice

Published on December 28, 2016   20 min

Other Talks in the Series: Aging

Hello again to this second part of my talk on studying human aging. As trailed at the end of the first part, I'm going to discuss three examples in order to help you apply the lessons you've learned from the methodological issues we discussed in the first half of this talk.
Now I'd like, in the next few slides, to give you three examples to draw together some of the themes that we've discussed around in the way aging develops and the challenges of measuring aging in humans and the challenges of undertaking robust study designs. Now the first example is about calorie restriction. Now calorie restriction in animals, restricting their diet to such an extent that they remain healthy and have a balanced diet and have very little adiposity. That has been shown repeatedly to increase longevity in most mouse models. I'm sure this will be covered in some of the other talks in this course. It's very clear from mouse experiments that being lean increases survival. And the same is pretty true in humans, that is, humans in the normal weight range, so a body mass index from 18.5 to 25 have lower mortality than those who are overweight or obese in midlife, and obesity and being overweight clearly increases mortality and a whole range of disease processes midlife. However, there's a major apparent paradox of obesity in later life. For example, Flegal et al., meta-analyzed a huge number of studies of obesity and reported that grade 1 obesity, that's body mass indexes between 30 and 35 overall were associated with high mortality in 65-year-olds and older. How is it possible that the experimental data shows that obesity is bad for you and the observational data in later life shows the opposite?