There’s been a variety of sound diet advice in this thread already, but I figured I’d add in the following. These are quotes from the diet plan you linked to, how many of them sound rational:
“it will clean out your system of impurities”
-Meaning what? What impurities and how are they being “cleaned out”?
“This soup will not add calories.”
-Uh huh. Sure it doesn’t. Go look up the calorie content of beef broth, green beans, carrots, etc.
“The secret lies within the principle that you will burn more calories than you take in.”
-Well no duh. That is how you lose weight and I hate to break it to these guys but it’s a pretty poorly kept “secret”. Of course they don’t say a thing about exercise or activity or how to actually burn calories.
“Due to the variety of digestive systems in individuals, this diet will affect everyone differently.”
-Variety of digestive systems? What, some people have five stomachs, others have a craw, there’s those guys who spit digestive enzymes on their Magic Vegetable Soup and absorb the nutrients through their epidermis…? And the “will affect everyone differently” gives them a perfect out if it just doesn’t work.
I doubt very much that you can actually lose 10 pounds of fat in 7 days following that plan (or any other plan, realistically). As others have said, that requires burning off 35,000 calories of stored body fat in a week, so 5,000 calories per day.
If you are currently eating 5,000 calories per day (that’s a lot of food) and getting zero exercise, you would have to STOP EATING COMPLETELY to lose that kind of fat in a week, without changing activity level. This is incompatible with their plan of eating all that soup, milk, fruit, juice, baked potatoes and butter, “2-3 steaks” and so on.
You may be able to drop 10 pounds in a week, but perhaps that’s from emptying your bowels and losing a lot of water weight. Geeze, I routinely come back from a run having sweated off 5+ lbs in a few hours (over and above all the fluids I take in while running), never mind one week.
My opinion, I think that diet is pretty dodgy. Talk to your doctor, make the sensible long-term changes you were talking about (healthier foods, portion control, increased activity as appropriate for you) and aim for a reasonable weightloss goal, keeping in mind that it’s a long-term goal; you didn’t put on the extra pounds overnight, they aren’t going to come off overnight either.
1-2lbs per week is a common recommendation for a safe rate, but even 0.5lbs a week is still 26lbs per year. That’s huge. And if you can make those changes in your life and stick with them over the long term I think that you’re more likely to keep the weight off since it wasn’t a “magic fix”.