Last reviewed on January 21, 2016
Here we are again; resolution season. It is that time when we resolve to take extra weight off ourselves and our pets. Most of us, and our pets, will fail miserably at achieving long term results, but may celebrate some short-term victories. And, actually, that may not be as bad as we think.
The yo-yo cycle of weight loss and weight gain is still healthier than no weight loss at all. A recent study in mice showed no life expectancy differences between weight controlled individuals and individuals that experienced repeated weight loss and weight regain cycles.
The Yo-Yo Diet Study
Mice were divided into three feeding programs for their entire lives. One group was fed a low fat diet and maintained at a normal body weight. A second group was fed 4-week cycles of low fat diets and high fat diets and experienced a yo-yo cycle of weight gain and weight loss. The third group was fed a high fat diet and maintained a lifetime overweight status.
The high fat, overweight group had significantly shorter lives. The lifespans for the low fat and cycled groups were the same. Blood markers for insulin and glucose tolerance and hormonal changes were favorable in weight loss cycles in the yo-yo group. Despite spending half of their life overweight, the yo-yo group still benefited from the improved metabolic changes that occurred during dieting. Chronic dieting did not have any adverse effects on lifespan.
What Does This Tell Us About Dieting?
Obviously the ability to expand these findings to other animals and humans is limited. Such studies are limited in longer-lived animals and human studies seldom span more than 25 to 30 years. But other related research may indicate that these findings are relevant to other species.
Massive amounts of research in many animal species and humans document the immediate beneficial effects of weight loss. Blood markers for insulin and glucose tolerance, and favorable metabolic and hormonal changes immediately improve. Fat inflammatory markers immediately decrease. There is little doubt that these positive changes would have beneficial health effects and possibly improve lifespan outcomes.
Also, studies in dogs and cats substantiate that the chronic overweight or obese state does indeed shorten lifespans by almost two years. Human studies also suggest that obesity significantly impacts lifespan.
So we know that no matter how often or how much we work to control weight it has a positive health effect. We know that if we do nothing, a shortened lifespan is a probable certainty. What we don’t know is how much time being spent overweight or obese is enough to affect lifespan. Future research may or may not answer this question for us or our pets.
If we are like the mice, then 50% of our lives spent overweight or obese is not enough to shorten life. So is it 60-75% or 76-99%? Or are we and our pets unlike mice and less than 50% of our lives spent overweight or obese is enough to affect our lifespans? We may never know.
What we do know is that doing nothing is not an option. No matter whether our efforts lead to permanent success, we can only help ourselves and our pets by the continued efforts. Any and all attempts to lose weight and eat healthy in the New Year will help. Good luck.
Dr. Ken Tudor