Action News sat down with a mother and daughter on the diet and also a local expert to see what he thinks of it.
53-year-old Nancy Carullo proudly showed off her new clothes she had to buy to Action News because the old ones just don't fit anymore.
She's lost 28 pounds since February and says it's all due to the 4-Hour Body diet plan.
"I feel like a new person, I really do," Nancy said.
And she's not alone. Her 17-year-old daughter Sally also follows the plan.
"I've lost 30 pounds since April," Sally said.
In The 4-Hour Body author Tim Ferriss unabashedly writes he is not a medical doctor or a PhD, but more of a lifelong guinea pig.
His diet plan restricts white carbs such as bread and pasta and also bans wheat and oats.
Fruit is also not allowed nor is dairy, except for cottage cheese.
Red wine is okay and protein, beans, and legumes are encouraged.
Plus you get a cheat day - one day each week to eat whatever you want.
"We like to make pizza and eat cake, donuts, stuff like that, you know the fattening foods," Sally said.
We asked Gary Foster, Ph.D, a researcher at Temple's Obesity Center, what he thought of the diet.
One of his main concerns is Ferriss suggests the plan is easy or effortless.
"When anybody says it is effortless to lose weight, change your intake or to change your activity level, it's not likely to be true," Foster said.
And as for cutting out some food, but eating lots of others, Foster says it all comes down to cutting calories. There is no single food that is the key to weight loss.
"So whether it is a low carb diet, a high protein diet, a high this or a low that, it is about cutting calories and if this approach does that, and for many it might, it will be an effective weight loss strategy," Foster said.
But both Nancy and Sally say they don't feel like they are cutting calories.
"On this way of life eating, I can eat a lot. I am never ever hungry," Nancy said.
While Foster does say there is some good advice in the book such as eating the same meals frequently throughout the week, he does not recommend the diet. He says the six days on, one off, may not be healthy or sustainable in the long run.
The Carullo's aren't taking what the critics are dishing out; they're happy and will continue following the 4-Hour Body.
"Some of my close friends at school will say 'Sally, you look great' and it's really nice to hear that," Sally said.
Both Dr. Foster and the author of the book say if you want to try this diet, check with your doctor first.
Action News did reach out to Tim Ferriss for this story but was declined our request for an interview.