Tuesday, November 22, 2005

Women Prefer Fat for Energy

In the study, 17ß-Estradiol Supplementation Decreases Glucose Rate of Appearance and Disappearance with No Effect on Glycogen Utilization during Moderate Intensity Exercise in Men, conducted by research teams from McMaster University and University of Geulph (both in Ontario, Canada), researchers set out to see if the hormone estrogen influences substrate (fat or glucose) selection for energy.

In a randomized, double-blind, placebo-controlled setting researchers investigated whether supplementation of estrogen given to men would effect glucose turnover and net muscle glycogen in eleven men over a period of eight days.

The result was intriging.

With estrogen supplementation, the fuel selection of the men was altered - to an increase in lipid use with a reduction in carbohydrate use. Alos, a reduction in glucose rate of appearance, primarily in the liver, and a reduction in glucose rate of disappearance, primarily in muscle uptake, was also noted. One last important finding was in the basal level of total muscle glycogen in study subjects - it was reduced.

Now the good part - what this all means and the reason for my headline.

While the study was done on male subjects, these results suggest that women are designed to have a preference to burn fat for energy - estrogen stimulates and influences the substrate preference for fat. It also helps to explain why women often have a hard time losing weight - especially when they eat a higher carb diet - and why they so easily gain weight when they eat excessive carbohydrate in their diet.

Quite simply, it is how their bodies are designed to work with their estrogen.

As this study demonstrates, estrogen stimulates the selection of fat for energy. But, if the right fuel is not eaten, the body is at a disadvantage for energy selection and use - I've said this many times before, that it is important to provide the body with the right fuel!

For women, that fuel is preferentially fat and a higher carbohydrate diet will inhibit this. A reduction in carbohydrate with adequate protein and fat in the diet will make all the difference. It's called controlled-carb nutrition and it works to bring that balance of fuel for energy, especially for women.

1 comment:

  1. Don't forget that during moderate and high intensity exercise the body uses carbohydrates as the number 1 energy source. Without adequate / full glycogen stores you will "bonk" and not able to finish the session. Even during low intensity exercise, some carbohydrates are required to metabolize fat for energy. Many "exercise experts" like to say that training with low intensities should be used for weight-loss. This is really a inadequate answer. At low intensity the body does use more fat as energy compared to carbs, but it also burns a lot less total energy. Because of this, low intensity sessions need to be at least 2 hours of duration in order to be effective. Higher intensity exercise will burn more total energy and is more time efficient for people that cannot train full-time. In order to train at high intensity, the body needs carbs, not fat as energy.