OP, I had amazing success with The Scarsdale Diet - a super easy, and fast, Diet from the 1970s. You can buy the book on Amazon for 99p. He tells you what to eat each day (just the ingredients, not portions or how to cook it) for 2 weeks.
For example, on Sundays you'd eat:
Breakfast:
Grapefruit, or fresh fruit in season.
One slice low-carb bread.
Coffee or tea.
Lunch:
• Cold or hot turkey or chicken
• Tomatoes, carrots, cooked cabbage, broccoli or cauliflower
• Grapefruit, or fruit in season
• Coffee/Tea/Diet Soda/Water
Dinner:
• Plenty of broiled (grilled) steak, all visible fat removed before eating; any cut of steak you wish- sirloin, porterhouse, London broil, etc.
• Salad of lettuce, cucumbers, celery, tomatoes (sliced or cooked)
• Brussels Sprouts
• Coffee/Tea/Diet Soda/Water
I found it so easy, and the weight falls off. It's low-calorie and low-carb, and it teaches you to eat in a completely different way, which is regally easy to carry on when you're all thin and gorgeous.
I lost 3.5 stone in 4 months and kept it off for 8 years!
I really wouldn't do the shakes/replacements - you're really setting yourself up to regain it all when you start actually eating again.