If it promises you to lose weight without limiting your calorie intake (e.g. have your weight loss cake and eat it too), then yes.
>but "use our magic equations based on state of the art info from 1958 to calculate your daily food needs and all your food and exercise as numbers and if your equation balances you'll lose weight" isn't
The laws of thermodynamics don't change because we don't have good formulas to calculate the exact amount of calories a person has a basic metabolic rate just based on their weight and height...
Calories still matter, and you should still limit your intake -- whether you do it approximately by "state of the art info from 1958" or with modern medical tests and expensive equipment. Or you know, just with eating less that you normally do, even without counting calories (if you ate 1 steak per day, and you change it to 1/2 a steak, you're eating half as much calories, even if you don't know how many exactly). Skipping BS deserts will cut even more...
No great science required, millions of people have lost way by just eating less...
If you're already very fit and lean, but have some stubborn fat around the "love handle" area or elsewhere, "eat less" doesn't cut it any more. Sure you can reduce that area, but not completely, and while the rest of you turns into an ugly skeleton.
The latter people are then delluded, surgery aside, you can't lose targeted fat from a specific body area. You lose fat across your body AND from that area, or you don't lose fat.
At best, you can trait that area and build some muscle next to the fat.