Of course you know that breed of people that eat with a certain degree of keen obsession, but never seem to gain weight. You will come across them this festive season, but experts say adding weight varies from one person to another.
Ababach Tamiru, a dietitian-nutritionist from Nilishe Health explains that some people can't gain weight no matter the consumption of food largely because they have faster metabolic rates-and the higher one's metabolism is, the more calories burnt and the harder it is to gain weight.
She adds that some people eat and shortly get hungry as their bodies use up food quickly causing them to get hungry meaning this way, no food is reserved to gain weight.
Genetics also plays a part in weight gain and determining natural body type, according to a 2019 study in PLOS Genetics whose research noted that over 250 different regions of DNA can be associated with obesity.
The researchers examined data collected from 1622 healthy people with low body mass index, 1985 people with severe obesity, and 10,433 control people or normal weight.
At the end of the study, they concluded that thin participants had fewer genes associated with weight gain and no matter how those born skinny feed, they can hardly add more weight due to genetics.
Clinical nutritionist, Antony Omondi Ouma from Diabesity Nutrition Clinic, explains that the inability to put on weight also stems from underlying health conditions ranging from diabetes 2 and hyperthyroidism.
In the case of diabetes, Ouma says insufficient insulin means glucose can hardly be absorbed from the blood into the body's cells to use as energy. As a result, the body starts burning fat and muscle for fuel, contributing to malabsorption and low weight gain.
In hyperthyroidism, the thyroid gland affects one's metabolism through the hormone it secretes when it produces too much thyroxin and the metabolism speeds up, increasing appetite and leading to limited weight gain.
"Some people have trouble absorbing nutrients making it a hilly ride for them to add weight," Ouma says, adding that eating food is not just about swallowing what's on the plate, as the body also has to absorb the nutrients, a process which can be impaired by inflammatory bowel disease and cystic fibrosis which can affect nutrients absorption leading to near zero weight gain.
Ouma says some people also suffer "physiological problems including stress and emotional eating disorder" leading to no weight added as emotional eating in response to emotions than hunger can lead to weight issues as the eating is for the wrong reasons as we are eating when we are bored, sad or happy not just when we're hungry.
Tamiru also lists chronic stress whose increase releases the stress hormone cortisol which is responsible for breaking down muscle and storing fat and thus those under a lot of stress can hardly add weight.
Frequent physical activity, says Florence Akeyo, a human nutrition and dietetics specialist in Migori County, burns more calories and as you equally continue eating to cover up for the lost calories, makes it hard to gain.
Prof Kathleen Melanson, a lecturer in nutrition and food sciences at the University of Rhode Island, says those who engage in active physical activities like regular cardio exercises burn more calories than 'couch potatoes' and thus deplete their calorie surplus needed for weight gain.
Types of foods eaten also matters as it's not about how much you eat:carbohydrates without proteins will only make one survive, but not gain weight.