No it is not true. There is no one specific factor that contributes to obesity. Obesity is the consequence of taking in more calories per day that your body can utilize.
It is vital to understand that sports drinks contain high levels of sugar. It is also intended to provide some hydration and electrolytes during physical activity as and when the body needs it and when the body can make use of the calories that is provided within the sports drink. Sports drinks must be seen as a purpose specific beverage and not as a social at random drink.