Yeah - they are some, which are bound to work. Personally I have only experimented with useful normal-day supplements, but at higher doses (RDAs are a joke).
The problem with those fat burners is that you can apply them only for a shorter time as some have high doses of herbs and caffeine which can strain your heart. You absolutely must not have a heart condition. And another important point is that many of them will in fact create greater hunger as they speed up your metabolism. Coffee without sugar for example is one such thing. You can drink plenty of it and will see fat being burned away if you couple it with exercise. But it will also impact your blood sugar level and you will experience hunger pangs.
So essentially you will need more willpower, but you have a chance to lose weight faster at some periods where you break through plateaus.
Personally I like the style and contents of the Grenade Thermo Detonator:
Gotta buy myself one of those babies to store my supplements in. Aside from the fun design the ingredients with decent herbs, amino acids and nutrients certainly can help you supplement your exercise routine. But don't let it fool yourself - it has massive doses of caffeine:
Supplement InformationPer 2 caps:
Green Tea500mg - CONTAINS CAFFEINE AS WELL
Bitter Orange Powder420mg
Caffeine225mg - PURE CAFFEINE
Cayenne200mg
Phenylalanine25mg
Green Coffee10mg - CAFFEINE AGAIN
My estimation is that you get some 350mg of caffeine - more than 1 liter of Red Bull - just without sugar. You should definitely take a high potency multi by Swanson, Now Foods or Youngevity in order to couple the aftereffects. Also you will experience strong hunger pangs occasionally.