How would one write a thesis statement that bariatric surgery (weight loss surgery) is not the easy way out?

Based on your question, I am assuming you want to write an argumentative claim. This is a type of thesis statement that includes a clear position and reasons to support that position. You have already indicated a position, which is in favor of bariatric surgery as a means of weight control.
There are several reasons why bariatric surgery is good for patients with obesity. One of these is that it stabilizes blood sugar and blood pressure while often eliminating sleep apnea. All of these conditions can adversely impact one’s health. The dramatic weight loss effect of bariatric surgery helps sufferers combat these conditions efficiently.
Another reason bariatric surgery is good is that it actually helps patients’ keep the weight off more effectively than traditional diets. Patients who have been obese for extended periods have lower metabolic rates, which makes it more difficult to maintain drastic weight loss. While not true in all cases, there is some research that indicates that metabolism does not hinder patients weight loss after undergoing bariatric surgery.
The biggest reason why bariatric surgery is good is because sometimes people have barriers to traditional weight loss that they haven’t been able to overcome on their own through diet and exercise. People whose lives are on the line because of their obesity-related health problems should be given the choice to have bariatric surgery because it is a relatively safe, effective procedure that would allow them to quickly address the problem that is adversely impacting their quality of life.
To put these reasons in a thesis statement, I would suggest using a stem that fills in the blanks with reasons:
Although many criticize bariatric surgery as the “easy way out,” bariatric surgery is good because _____________, ____________, and _____________.