I read an interesting study on the links between insulin levels and weight. The researchers suggest that a high insulin level is negatively associated with weight gain, which, in turn, suggests a high-glycemic diet is a benefit to those attempting to lose weight. I don’t have access to the full-text version, but the abstract alone left me scratching my head.
Reduced insulin secretion: an independent predictor of body weight gain
Relatively reduced insulin secretion, therefore, is a significant and independent predictor of the tendency to gain weight and adiposity in Pima Indians. The presence of relative insulin resistance also conferred an independent reduction in the risk of weight gain in some regression analyses. We conclude that insulin resistance and hyperinsulinemia are unlikely to play a causal role in the development of obesity, and that relatively reduced insulin secretion is a marker of an increased risk of weight gain in this population.
Without knowing the methodology of the study, it’s impossible to say how (if at all) the researchers controlled for the high rate – 50% + – of insulin-resistance among the Pima Indians. It’s also impossible to say if they found any causal or correlative relationship between the insulin-resistance and weight-loss, but failed to mention it in the abstract.
However, it’s clear that the researchers wanted to drive home the point that a high insulin-level conferred weight-loss, while a relatively reduced level was at least correlative to weight-gain. Let’s take a look at why this could be.
In an even cursory examination of the initial effects of Type II Diabetes, it’s obvious that a high-insulin level is correlative to weight-loss. Type II diabetics are insulin resistant – their cells do not respond to the insulin as do the cells of non-diabetics. In a normal individual, insulin drives the use and storage of circulating blood glucose, which results in blood glucose spikes and drops and, eventually, weight gain.
In a diabetic, though, the cells don’t respond to insulin. The circulating insulin can knock on the cell’s door all the day, demanding it take in the circulating glucose, but the cell won’t respond. This leads to incredibly high blood glucose levels and weight loss. Since the cells aren’t taking in the easily utilized glucose, they fall back on fat stores. The utilization of fat stores releases ketone bodies, which, in uncontrolled diabetics, results in ketoacidosis.
In another study that examines the relationship between weight gain and Type II diabetes, the researchers note the different responses to insulin among different ages. In the young, most studies conclude that high insulin levels are positively associated with weight gain. In the aged, many studies show, to one degree or another, a negative association between the two.
Obesity and Weight Gain Are Associated with Increased Incidence of Hyperinsulinemia in Non-Diabetic Men
On the contrary, higher levels of insulin predicted a gain in body weight and obesity in Pima Indian children [9] and in U.S. black and white young adults [12]. It has been suggested that hyperinsulinemia promotes weight gain in children and young adults, and that subsequent increase in insulin resistance and compensatory hyperinsulinemia then limits further weight gain in adults [9, 27].
The simplest explanation is that the young are not insulin-resistant and their cells respond to the call to store the glucose. As we age, we develop insulin-resistance and our cells are unable to utilize the circulating glucose. The former will result in weight gain, while the latter will result in weight loss.
If we’re solely concerned about achieving a healthy weight, then older individuals should aim for a higher insulin level. A high insulin level will encourage cells to stop responding to the insulin and utilize stored fat for energy. However, as the researchers note, high insulin levels come at a price.
These prospective population-based data emphasize the importance of avoiding obesity and weight gain during adulthood to prevent hyperinsulinemia [excessive insulin production] and, eventually, type 2 diabetes.
The high insulin levels may aid in short-term weight loss, but excessive insulin is a known precursor to diabetes. I’m still searching for the full text of the original study, and hope the researchers addressed this problem.