How do you know if you get enough nutrients? – Doing Nutritional Assessment
To understand nutrition properly, we need to approach nutritional assessment scientifically. You can think of this as two processes:
- Assessing our diet (measuring and assessing the food we eat)
- Assessing our nutritional status (the body’s status in relation to diet)
Assessing our diet
A good method is to keep a ‘food diary’ for a week, and write down all the food and drink that you have had. By doing this it is possible to see how much of the macronutrients and micronutrients you have on an average day and compare this to recommended amounts.
Adjustments can then be made to increase or decrease any element of the diet as required. The overall goal is to achieve the optimum intake of nutrients to support health and well-being.
A variety of free online and purchasable software is available to check your food diary results, however the process can be quite long and confusing if you are not accustomed to scientific language and figures. For this reason, dietary analysis is usually best carried out and interpreted by a dietician or a qualified nutritionist and then explained in a consultation.
Assessing nutritional status
This entails make measurement of the body and blood and relating results to our diet.
A simple example is Body Mass Index (BMI) which calculates ‘weight for height’ of a person. The simple formula is Weight(kg)/Height(m)2. A BMI of below 19 usually means underweight while a BMI of over 25 indicates excess weight, above 30 obesity. This is a useful measure for groups of people, but can mislead for an individual. For example, a very muscular man may have a BMI of 30 but not have any excess body fat. Equally a pregnant woman may have a BMI of over 25 but in no way be overweight.
Perhaps a better way to do nutritional assessment, also very simple, is the waist to hip measurement. A simple measure of the waist (around the level of the navel) divided by the hip (around the level of the largest part of the buttocks). A high waist to hip measure (i.e. a big tummy compared to bum) is a sign of risk to health. On the other hand, a low ratio (small waist, bigger bum) is an indicator of lower risk to health.
From puberty to older age, women tend to have higher waist to hip ratios. This reflects a higher risk of heart disease. Research shows fat stored around the tummy area is risky for heart disease, but also for diabetes. Even keeping an eye just on waist measurement can be a useful indicator of disease risk.
|Women||˂ 0.85||˂ 0.85-0.90||˂ 0.90-0.95||˂ 0.95-1.00||> 1.00|
|Men||˂ 0.75||˂ 0.75-0.80||˂ 0.80-0.85||˂ 0.85-0.90||> 0.90|
Total body fat measurement
We can also measure the percentage of our total weight that is body fat, on bioelectrical scales at the gym, the doctor or available to purchase. While these aren’t generally accurate to the clinical level, you can still get a good rough idea of your % body fat, and certainly see whether it is going up or down over time.
As well as measuring the body directly, clinicians and clinical nutritionists may also wish to measure blood.
Blood tests can be really thorough, but for nutritional assessment there are a smaller number of key tests to be aware of.
If you wanted to test your blood at home there are a couple of useful resources. In the USA Walgreens offers blood testing kits and in the UK you can test with Thriva, who also offer great service.