Early adolescence is often a time when we create lifelong habits.
Excessive time in front of the television should not be one of these.
Long-term studies have shown links between obesity and time spent in front of the television. Monitoring 2439 children, ages 14-21 years old, one study focused on t.v. time and its association with BMI, waist circumference, waist-to-hip ratio and obesity. In fact, the journal states that “children including preschool children who watched the most TV had the greatest increase in body fat by early adolescence”. 
Another study conducted in Spain analyzed 10,791 individuals, 18 years of age and older from 2008-2012. The objective of this study was to examine the association of obesity-related eating behaviours with physical activity, sedentariness, and diet quality. Obesity-related eating behaviours were defined as follows: not planning how much to eat before sitting down, not deciding the amount of food on the plate, skipping breakfast, eating precooked/canned food or snacks bought at vending machines or at fast-food restaurants, not choosing low-energy foods, not removing visible fat from meat or skin from chicken, eating while watching television or seated on a sofa or an armchair, and taking a short time for meals. Individuals with five or more obesity-related eating behaviours (compared to those with 1 or less obesity-related eating behaviours) had less physical activity and spent more time watching television, as well as attaining a higher total energy intake. 
Another possible variables I feel should be accounted for include whether the snacking is in moderation, if the snacks are healthy, and if this person is eating in excess/spending more time in front of the TV partially due to depression. Although I’ve only cited 2 articles, I’ve read through several scholarly journals studying the correlation between television and obesity – feel free to search more if you are in doubt!
Limiting TV to one hour a day can also avoid exposure to unhealthy & misleading food advertisements, unnecessary indulgence, improved sleep patterns (it is always best to avoid screens right before bedtime), and much more. Not to mention, if you are not alone, avoiding the tv may force you to actually have interactions and talk to the person next to you, fostering a healthy relationship. Think about what you watch on tv these days anyways–all reality garbage. It is very possible that you are being brainwashed and [definitely] wasting brain cells, turning into the characters you see on tv and imitating their ways without realizing it! Choose what you watch carefully.
1. Mamun AA, O’Callaghan MJ, Williams G, Najman, JM. Television watching from adolescence to adulthood and its association with BMI, waist circumference, waist-to-hip ratio and obesity: a longitudinal study. Public Health Nutr 2012; 1-11.
2. Mesas AE, Guallar-Castillón P, León-Muñoz LM, Graciani A, López-García E, Gutiérrez-Fisac JL, Banegas JR, and Rodríguez-Artalejo F. Obesity-related eating behaviors are associated with low physical activity and poor diet quality in Spain. J Nutr 2012; 142(7):1321-1328.