There is a lot of focus on encouraging people who are overweight or obese to get their weight within the healthy range, but this aim is equally important in those who are underweight because having a BMI under 18.5 increases the risk of health problems such as osteoporosis, anemia and fertility issues.

It is important to work out why someone is underweight in the first place €“ if they have lost weight without trying to do so they may have a condition such as an overactive thyroid gland, a digestive disorder such as coeliac disease, or a more serious condition such as cancer.

If they have lost weight intentionally and don't grasp that they have gone too far, this could indicate an eating disorder. Pharmacy teams should provide advice on sensible ways of gaining weight, such as regularly eating more foods that are high in nutrients and energy, and possibly taking multivitamin and mineral supplements. If concerned about someone who is underweight, refer to the pharmacist.