Body Composition, not Body Weight

You may think being on top of age means being weight obsessed. But in reality, it is the quality of what your body consists of that is important in terms of limiting ageing.

The key is having a sense of how much muscle [positive] you have and how much central fat [potentially damaging] you have gained.

So the number on the scale is less important  as long as you are travelling in the right direction.

Forget BMI – measure your waist and can calculate your waist /height %

Please don’t use the body mass index [BMI] to judge where you are. My own BMI, for example, is 26. You might at this point wrongly conclude that I am fat and ‘overweight’.

In fact, I have an acceptable body fat percentage of 22% [on a Dexa scan] but have built up muscle that makes me heavier. A better test is putting a tape measure around my waist. My measurement of 92 cm is 51% of my height of 180 cm. The ideal is 50% or less so I have a little work to do but am close to ideal.

This waistline approach measures central body fat which is important because it is metabolically active in a negative way. Central fat increases inflammation and influences other health issues eg it increases insulin ‘resistance’ [of which more another time], blood pressure and cholesterol levels.

This means there are two issues of concern to age-defiers as you count the birthdays: how much muscle have you lost and how much fat have you gained compared with your young / pretty fit stage.

Muscle loss is dangerous

Muscle loss or sarcopaenia [sarco = muscle; paenia = lack of] means loss of strength [another Latin word – dynopaenia] and losing strength is the beginning of the slippery slope to weakness, falls and loss of independence. Critically, dynopaenia is not inevitable as we age it is a ‘disuse’ problem and is therefore avoidable.

Well, that is part of the story: lost muscle can always be replaced by weight bearing exercise and resistance training. However there is another actor on the stage here – your sex hormones.

​​​​​​​Hormone effects on body composition

Women lose oestrogen at the menopause and both men and women lose androgens gradually from the late 30s. Both types of sex hormone are important in both sexes although operating in a different ‘balance’. At menopause the impact is that metabolic rate falls, insulin metabolism changes and there is an increase in body fat: muscle mass falls like bone mass by between 1 and 3% a year. In men the gradual fall in testosterone means that metabolic rate and muscle mass are falling. So for both sexes unless there is positive corrective action ie careful nutrition and muscle-maintaining exercise, body composition alters unfavourably.

Hormones can help

Hormone replacement for men and women has often had a bad press. Current expert opinion is that there are no major disadvantages or risks in healthy individuals. The question of hormones if you are 60+ will be a topic on its own, soon.

Key messages

• Aim for a waist/ height percentage of 50% or less [imperial or metric]
• BMI is not a very helpful measure
• As we age, metabolic rate falls so we cannot eat the same carbohydrate load
• Add muscle-building exercise to your fitness regime – use it or lose it!
• Look out for the InfoSheet on hormones