The rising problem of obesity is causing major health problems, reduced quality of life and reduced life expectancy. It now generates approximately 10 of all health costs. The progression of the problem indicates preventive measures have been unsuccessful so far. Only bariatric surgical treatments have been able to achieve substantial and durable weight loss. Gastric banding and gastric bypass are used in more than 90 of bariatric operations. The proportion of each varies from greater than 95 bands in Australia, about 50/50 in Europe and USA and nearly 100 bypass in South America. The availability of follow up is a prime determinant of choice. Understanding the mechanisms of effect for the bariatric procedures is central to optimizing their effect.