The V-Diet definitely is effective!
But here's why I've chosen Lyle McDonald's Rapid Fat Loss diet over the V-diet, twice, when trying to lose weight in a hurry:
Solid food (lean protein; limitless fibrous vegetables; very small amounts of corn, beans, peas, beets, carrots allowed).
Only supplements suggested are table salt, Mg, Ca, K, and a multi-vitamin. I only use the multi-vitamin as I get the electrolytes from fat-free dairy, green leafy vegetables, beets, and tomatoes.
One cheat and one five-hour refeed-carb-up per week. I consider this VERY enjoyable.
Six grams of fish oil per day. I get this from a serving of salmon, trout, or sardines; no Flameout needed.
So, instead of not eating solid foods for weeks on end aside from four meals out of the four weeks, I eat whole foods 5 to 6 times per day, save hundreds of dollars, and have fun with carbups and cheat meals, all while losing weight at warp speed.
The one detriment of the diet is that it's more restrictive than the V-Diet in caloric intake; I've ingested 1,200 kcals per day on the diet at times; the V-Diet calls for 1,600 to 2,000 kcals per day for my bodyweight, 225#.
I've used no thermogenic each time. I lost no lean mass or strength on the diet. Training was scaled back to twice per week though with a full body routine. Intervals were done twice per week after weight training, 60 second work: 120 second coast ratio. NEPA is done on off days.