From a fellow dietitian:
"I do believe there are significant risks for mortality with increased BMI, irrespective of diet. I have seen studies supporting that, so I don’t think it’s a slam dunk for embracing any level of obesity. See the latest BMJ systematic review for example:
My fingers get twitchy when I see this kind of research used to justify recommending weight loss, but I see it all the time and I think it's important to unpack the details.
The meta-analysis you've posted is a good one and can tell us many things. Mainly it shows that a group of larger people is, on average, likely to have a shorter lifespan than a group of smaller people. Interestingly, this one shows that smoking appears to be worse for you if you have a high BMI. The identification of the nadir of risk is great news for people who have a lower BMI relatively effortlessly despite living in an obesogenic environment that causes 2/3 of the population to creep up in weight over time (ie genetic jackpot). The recent influx of big BMI and mortality meta-analyses interestingly comes in response to Flegal's paper from 2013 which found that being overweight conferred the lowest risk of death in an NHANES dataset, thus suggesting that larger bodies might not b