When You Lose Weight: Does it Make You Live Longer?
Competency #1: Know Your Ideal Body Size
Reference: JAMA. April 5, 2006, Heilbronn et al.
This is a complex question that has been hotly debated. In many small mammals, calorie restriction leads to markedly longer life spans, as much as 30%. Does that apply to humans? Is it worth it to lose weight? We have population studies that show a virtual linear relationship with risk for heart disease, cancer and Alzheimer’s with increasing weight. But how does weight loss and gain help? We have “associations” and “assumptions” and “population studies”. We haven’t had direct proof. We haven’t had proof that total energy expenditure is reduced in humans after weight loss. Nor have we had proof that markers for various kinds of stress are improved with weight loss. But one of the going theories is that we gradually damage our bodies over time with oxidative stress. About 1-2% of our oxygen consumption gets turned into free oxygen radicals, and that damages our DNA, our proteins, our membranes. We can show that this happens. And we can show that eating lots of anti-oxidants reduces free oxygen radicals. (That’s why I buy blueberries. Last week it was all about the champion of antioxidant foods: blueberries)
NOW, we have some PROOF by experimental design in humans. This is a great leap forward. In JAMA, April 5 this year, a study was published from LSU in Baton Rouge by Dr. Heilbronn et al titled “Effect of 6 month calorie restriction on Biomarkers of Longevity, Metabolic Adaptation and Oxidative Stress in Overweight Individuals.” This is a cool study. 48 people were randomized into 4 groups for a 6-month diet intervention. Only 2 dropped out. The groups were: “control” (no change in diet), “calorie restriction” (25% less calories), “diet plus exercise” (12.5% calorie reduction with 12.5% increased burn by exercise) and “very low calorie” (890 calories until a 15% weight loss.)
Findings: Two biomarkers of longevity (fasting insulin level and body temperature) are decreased by prolonged calorie restriction. And reduced more so than change in body mass. Thyroid blood tests were in sync with the slow down, suggesting that our thyroid glands are pretty smart and are part of changing our body’s overall metabolic rate. That means that calorie restriction really does reduce your actual need for calories. We all know that. I try to lose weight and immediately find that my body gets along on less so I have to try even harder. And I get freezing cold at night and need another blanket. That’s very self evident to me. But it hasn’t been “proven” before. Now it has! And there is less DNA damage to boot. It doesn’t seem to matter which path you take. These changes occurred in all three study groups. And the changes were maintained even after the baseline was achieved. Losing weight to a lower body mass fundamentally changes your internal markers of stress and longevity. It works. The living longer question will have to weight, I mean wait, another 30 years. I haven’t got that much time to weight. I need to skinny up a little bit more.
WWW: What will work for me? This is basic science data that supports the concept of losing weight to add to longer-lived healthy life plans. It explains to me why it’s so hard to do too. The reward is worth it. It’s a life long journey. Back to my blueberries.