Obesity is an excessive accumulation of body fat caused by lack of exercise and poor nutrition. It is commonly diagnosed in teenagers who are 20% heavier than their ideal weight. The rise in obesity rates among teens is linked to larger portion sizes, sugary drinks and snacks, and less time spent being physically active. If obesity continues into adulthood, it can decrease life expectancy and increase health risks. While genetics play a role, individuals can fight obesity by limiting junk food, getting moderate exercise daily, and developing a healthy self-image and lifestyle habits. Education programs are needed to help motivate teens towards healthier choices.