Hormones and metabolism in females part 1

I’ve just finished a short course in this area and thought I could share with you some of the key points. I will break the info down into two blogs as there’s too much for one blog.

The most effective way to change your shape is to weight train.

Between the ages of 35 – 55 sedentary women increase fat by 1 kg a year, (doesn’t sound much, but 20kg of extra fat in 20 years; now that sounds a lot).

Between ages 45 – 65 sedentary women lose 2kgs of muscle a decade. By age 60, females could have half their peak muscle mass. This means a big reduction in resting metabolic rate (RMR).

1/2 kg of muscle utilises 35-50 calories at rest per day, 1/2 kg of fat uses only 2 calories.

Genetics does play a part in your chances of becoming obese. If one of your parents was obese you have a 40% chance of being obese, if both parents were obese your chance is 80%. So, one will have to work harder to overcome a genetic predisposition to weight gain.

Women have 10 – 20 times more growth hormone (GH) than men, which is required to increase strength, and thereby, metabolism.  GH allows stored fatty acids to be used as fuel, sparing glucose (carbs). High intensity weight training (up to 10 reps, a few sets, 60-90 seconds rest betweens sets) causes GH to be secreted at nearly 4 times the rate as when in a spinning class, or nearly twice as much as during running for the same time. Eating within two hours after weight training helps to release GH.

Women have 20 times less testosterone than men, which means it is difficult for women to increase muscle size. Women need not be too afraid about getting ‘big’ by doing weights, as it is generally very difficult for them to gain size. Women increase strength by increased number of muscle fibres (hyperplasia), whereas men increase strength by muscle cell size increase (hyperthrophy), which tends t0 lead to larger volume of muscle.

Oestrogen (a ‘fat storing’ hormone) fluctuates throughout lifespan and, overall, is dominant over progesterone, but especially in puberty and pregnancy. It starts to decrease during menopause. Progesterone, which counteracts oestrogen, is very low from peri-menopause onwards, and oestrogen tends to dominate, leading to weight gain, especially around the waist. There is some evidence that eating soy products can help increase progesterone levels.

Cortisol, a hormone released in response to stress, is a catabolic hormone, which means it breaks down muscle tissue, so avoiding stress is key to increasing muscle strength and, therefore, RMR. Very low calorie diets and lack of sleep also make the body produce cortisol.

Other fat storing hormones are insulin, (produced after eating, especially higher carb foods), and epinephrine (from the adrenals). Presumably avoiding fight or flight response, commonly known as stress, will reduce output from the adrenals. Iodine is a hormone that effects thyroid function and regulates cortisol release – a great deal of iodine is lost during childbirth and does not always return to healthy levels.

Fluctuating hormone levels can have an impact on thyroid function, which in turn has a strong effect on metabolism of carbs, protein and fats. It could be worth getting it checked if you’re over 35 and feel like you’re not getting anywhere with weight loss even though you’re training hard.

The good news is that despite the difficulties associated with various hormones we have the necessary hormone in abundance to build strength and slowly hike up your calorie utilising furnace! – that is Growth Hormone. Let’s get it fired up. Build strength, improve balance and stability and drive up bone mineral density with good old fashioned dumbbells.

More about this next week.

Lisa 🙂

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