Eating well but still struggling to gain weight? Doctor reveals when persistent low body weight signals underlying issue

Dr Eileen Canday warns that persistent low body weight paired with fatigue and muscle loss requires medical evaluation, stressing importance of a balanced diet.

When should difficulty gaining weight be considered medically significant rather than simply a 'fast metabolism'? Often, being thin is not considered a red flag for health, unlike gaining weight. However, even after eating well, exercising regularly, and increasing your macros, if you don't gain weight, it could be a signal of an underlying issue.

In an interview with HT Lifestyle, Dr Eileen Canday, head of the department of nutrition and dietetics at Sir HN Reliance Foundation Hospital, warned that if there is unintentional weight loss that surpasses 5% of body weight within six months or the BMI is less than 18.5 for those aged under 70 years, then it is medically significant.

She explained, “In case of persistent low body weight, fatigue, muscle wasting, and recurrent infections, it means that one requires a medical check-up to rule out underlying metabolic, gastrointestinal, or endocrine disorder. All these indicate the need for a medical check-up.”

Even with adequate calorie intake, people lack nutrients due to insufficient consumption of certain vitamins and minerals.

Thyroid disorders, diabetes and other metabolic conditions affect body weight?

According to Dr Eileen, various hormonal and metabolic diseases can significantly affect your body weight.

She explains that thyroid disorders affect body weight to a great extent. Moreover, in hyperthyroidism, the basal metabolic rate is elevated, resulting in weight loss despite normal or even increased appetite. On the other hand, hypothyroidism leads to weight gain mainly due to water retention without fat accumulation.

Diabetes, if uncontrolled, can lead to ‘muscle wasting due to the excretion of glucose and poor utilisation of nutrients’. “Moreover, insulin resistance can lead to fat distribution changes, leading to an accumulation of visceral fat but concealing undernutrition. In addition, digestive problems and malabsorption disorders influence body weight,” Dr Eileen added.

Can someone eat enough calories but still remain nutritionally deficient?

According to Dr Eileen, this can happen. She explained that it is referred to as 'hidden hunger'. “Even with adequate calorie intake, people lack nutrients due to insufficient consumption of certain vitamins and minerals. It happens with high carbohydrate intake and insufficient intake of nutrient-rich foods, leading to deficiencies in iron, vitamin B12, vitamin D, and zinc,” she added.

Moreover, gastrointestinal disorders such as celiac disease or Crohn's disease make people even more nutrient-deficient.

“People may consume an adequate number of calories from refined carbohydrates, sweet food, and highly processed products, but lack protein, fibre, vitamins and minerals,” she underlined.

To gain weight in a healthy way, one should eat several meals a day to increase their calorie intake. (Shutterstock)

How to gain weight without relying on ultra-processed, calorie-dense foods?

According to the expert, in order to gain weight healthily, one should follow these steps:

• Consume nutrient-dense whole foods, including nuts, seeds, avocados, whole grains, legumes, and lean proteins.
• Consume healthy fats in reasonable amounts, including olive oil, ghee, and nut butters, as they add calories without depriving one of nutrients.
• Eat several meals a day to increase your calorie intake.
• Follow a strength training program to increase muscle mass.
• Avoid relying on ultra-processed, calorie-dense foods, which may worsen micronutrient deficiencies and metabolic health.

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.