Excessive weight gain and extra fatty tissue are obviously the major symptoms of obesity. However, the weight gain causes a lot more symptoms to be manifest in the patient gradually over a period of time. As the disease advances, these become more and more prominent:

Running out of breath - even with minor exertion sometimes

Lethargy, tiredness

Difficulty in sleeping

Excessive perspiration

Pain in weight bearing joints like knees, hips and also in the back

Snoring

Sleep apnea

Rashes in the folds of skin such as in the groins, between thighs, axillae, below breasts, etc.

Depression

Low self esteem

Always feeling hot

Daytime sleepiness

Many other diseases are also associated with obesity and the patient may manifest any of the symptoms of these - heart disease, hypertension, stroke, cancer, gallbladder disease, type 2 diabetes, etc.