Combining very low calorie diets with frequent medical oversight to monitor progress and health, these intensely supervised programs are best suited to highly motivated individuals.  With strict adherence to a well designed regimen, significant weight loss can be achieved over a short period of time.

Indeed, one strong argument in favour of such programs is that when patients quickly achieve results, they become more motivated to maintain the diet regiment until weight loss goals are fully achieved. Such programs demand a lot of you. If you tough it out, you can can see very satisfying results.

On the negative side, because the programs are based on very low calorie diets or meal replacement supplements that can't be maintained indefinitely, fundamental eating habits are not changed. So graduates remain vulnerable to weight regain (that darn yo-yo effect again) just like other diets. As well, the nature of these programs make them more suitable for those with fairly modest less weight goals (under 100 lbs.)

Most (but not all*) medically supervised programs do come with a major educational component designed to encourage changed eating and exercise habits. In fact it is often a requirement for program participation. As well, most programs are held in a group setting which makes for a supportive environment, offers encouragement and facilitates discussion and idea exchange.

Bottom line: you can lose a lot of weight fast, improve your health, gain valuable psychological and nutritional education to better understand eating behaviours and guide your eating and exercise habits. 

And, seeing tangible results quickly could be just the added motivation needed for you to become one of the 5% of people who are able to permanently change their lifestyle, maintain their weigh losses and live a happier, healthier live there-after.

Buyer Beware: At least one weight loss program heavily advertised as "medically supervised" provides little in the way of supervision or education. Ask before you commit. 

I speak from personal experience with this clinic (albeit some years ago). Almost not existent supervision. Almost non-existent nutritional education. Never-the-less, I was able to lose about 40 lbs. –– which speaks more to strictly following their 900 calorie/day diet than anything else IMHO.

It took about almost 5 years to regain that weight. Note: I wasn't trying, it just happened :-(