Me and my body's reaction:
Cambridge Diet original version of 330 cal /day in 3 shakes - starvation, misery and rebound weight gain
Hunter Gatherer eating plan - felt great, but couldn't source the required quail, ptarmigan and wild boar
Hay Diet - felt great on his protein meals, dreadful on his carb meals
Vegetarian - lasted 12 months. Then ate chicken and felt the best I had for 12 months. Never looked back.
Macrobiotic - lasted 3 days. Life is too short to endure such misery.
Slim fast - felt dreadful. Reactive hypos. Gave up v quickly. Rebound weight gain.
Atkins - felt ok but kept with 1 slice bread and minimal veg = constipation. Gave up. Obviously wasn't doing it properly.
Dukan - felt good. Lasted a long time. Then fell back off the carb wagon.
Weight Watchers -

Bad reactive hypoglycaemia. Always cold. Regular hypos. Dreadful. Rebound weight gain.
South Beach - only did it to keep Mr B company. Far too many carbs (1 decent portion a day) felt dreadful. Had to give up.
Green Smoothies for lunch and brekkie, low carb for evening meal - felt GREAT. Lost interest in the smoothies when the winter drew in.
Generalised Low Carb - wow. Seemed to work for me. Would have been better if I'd had a meter!
Very Low Carb - even better.
The Diabetes Miracle -no more than 5g carbs per meal for 8 weeks. Felt fab. A bit too strict to be sustainable for me.
VLC no grains - where I am now. Seems to work the best so far.