2 years ago i went hard on optislim/optifast and lost nearly 50 kilos in just under a year and have kept the weight off. I am a big fan of liquid VLCD (very low calorie diets) as it worked for me brilliantly. Shakes (always chocolate) for brekky (mixed with 2 shots of freshly brewed espresso) and lunch religiously everyday, sometimes for dinner, but if not, then I ate very small and super healthy. I snacked a lot on salad vegies or had little tins of tuna mixed in with the salad stuff. I like optifast, but get better value buying 2 boxes of optislim for $55 from epharmacy.com.au. I still have a shake every morning for brekky and for lunch or dinner if my husband is at a meeting or working late and I don't have to cook. I think I found it an easy diet because I was a huge fan of choc milk.
A big motivator for me during that year was using 'wee-on-a-stick' ketodiastix (a diabetic friend can get a container of 100 for you for 50c or you can get them for approx $24 at full price at a chemist) They let you know very quickly if you are losing weight without having to wait for measurable differences on your scales or looser clothing. I educated myself about losing ketones and mixing a very low carb diet with a liquid VLCD and lost half of myself . I retrained myself to eat healthy and small and if you are motivated enough and tough enough then starting on shakes is a great kickstart to a lifestyle change. Best of luck!