There are so many issues around weight gain and loss, like why some people gain weight easily or lose it and others can’t. For example, one slim person who seems to have a hearty appetite, even with junk food, doesn’t seem to gain weight, yet another feels heavier just by looking at a picture of food? We always wonder about this, especially when we want to reach a preferred body weight. But, experts say, there are many reasons that can cause someone to gain weight or lose it, and among them, are things we do daily perhaps unknowingly. Jolie Esther Nandatwa, a physiotherapist at Physique Clinic, says that there are many reasons that cause weight imbalances in someone’s body. “There are reasons, like how active someone is; people who are more active will find it hard to gain weight because they balance their weight through exercise regularly, and that is why people who are less active easily gain weight. And, it also depends on someone’s eating habits, people that eat less but all the time gain weight easily because their body doesn’t know when to rest, eating at night can make you gain weight easily too,” she says. Nandatwa also explains that there are chronic diseases that could cause weight gain or weight loss. Eric Matsiko, a lecturer in the Department of Human Nutrition and Dietetics at the College of Medicine and Health Sciences, University of Rwanda, says that some people can be thin and others can be overweight, even though they seem to have the same diet. “We gain or lose weight when energy intake (food and drinks we take) and energy expenditure are out of balance, fluctuations in body weight are a result of changes in energy intake of the food and beverages consumed, and energy expenditure or the amount of energy expended on doing work. Energy balance occurs when energy intake equals energy expenditure, this means we consume the same amount of energy that we expend each day,” he explains. According to Matsiko, to lose body weight, we must expend more energy than we consume or eat, we must eat less energy than our body needs. In this case, we allow our body to use energy stored, our body stores energy we eat as fat so when the body starts using stored fats, in principle, we should start losing body weight. To gain weight, we must consume more energy than we expend. Excess energy is stored as fat which increases our body weight. According to Laurien Izere, a personal trainer, you should know your body type in order to know how you can transform your body. “Weight loss or gain require nutrition and training as well, and this acceleration of the process depends on your body type (genetics). We have three main types of body; the ecto-mesomorphs—this body type is lean and muscular; the meso-endomorphs— this means strong but the muscles aren’t well defined, like a football player, and the ecto-endomorphs—the “skinny fat” a person who is naturally thin but has gained weight due to lack of exercise and a poor diet,” Izere explains. Matsiko defines a healthy weight as a weight that is appropriate for one’s age and physical development—weight that can be achieved and sustained without severely limiting food intake or constantly dieting. A weight that is based on one’s genetic background and family history of body shape and weight. What makes us gain and lose weight? According to Matsiko, there are main factors affecting weight gain or loss: Energy intake: Food and drinks consumed, defined as the caloric or energy content of food as provided by the major sources of dietary energy. Energy expenditure: Mainly energy that we spend while doing physical activity. If we exercise more, we lose more stored energy, and this in the long run leads to weight loss. If we have a sedentary lifestyle, we are likely to gain more body weight. Genetic predisposition: Having genes that promote weight gain. This relates to a family history of having excess body weight.