Charles Darwin

There is no fundamental difference between man and the higher animals in their mental faculties . . . The lower animals, like man, manifestly feel pleasure and pain, happiness, and misery.

Body Weight, Obesity, and BMI

Body weight - person's mass or weight. Body weight is measured in kilograms, pounds, or stones and pounds. Body weight is the measurement of weight without items located on the person. 

Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health.

People are generally considered obese when their body mass index (BMI) is over 30 kg/m2, with the range 25–30 kg/m2 - overweight. 

BMI, body mass index - a measurement obtained by dividing a person's weight by the square of the person's height. 

Obesity increases the likelihood of diseases, particularly heart disease, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis.

Obesity is most commonly caused by a combination of excessive food intake, low levels of physical activity, and genetic susceptibility. A few cases are caused primarily by genes, endocrine disorders, medications, or mental illness. Evidence to support the view that obese people eat little yet gain weight due to a slow metabolism is not generally supported.

On average, obese people have a greater energy expenditure than their thin counterparts due to the energy required to maintain an increased body mass.