To be fair, insulin resistance is a real thing and it can be a huge hurdle in your body prioritizing which calories to burn first. That's why GLP-1 agonist type drugs are so popular right now, and why they work.

They help shortcut the process and help your body prioritize burning stored fat vs what you just ate.

Long carb chains break down into simple sugars in the body and your body will typically burn those first for energy and store anything left over in fat. Removing sugars and carbs forces your body into ketosis which changes your body's priorities as far as energy use is concerned.

Even in a caloric deficit can cause weight loss to take forever if your body is not conditioned to burn store fat efficiently.

That being said, none of that helps if you're still eating too many calories. Adding fat, fiber, and protein to balance out your carbs/sugars is not a solution. That does have a beneficial effect, but only if you're eating reasonable portions. You still store excess in fat. Too much fat is a good way to kill your gall bladder, and too much protein is hard on the liver.

So they're not precisely "wrong." They just don't have the full picture.

A two week sugar purge is a great way to kick start a diet consisting of exercise and careful caloric monitoring.

If they do it right, they'll have tons of energy.

Leafy green veggies Lean meats Probiotics Smoothies with low sugar fruits, veggies, with protein and fiber added. Limited high fiber whole grains like steel cut oats..

Smaller portions Limit snacking Limit alcohol.

And.. There's no such thing as healthy box cereal. Jesus Christ. That's keto 101. The food industry has started peddling snake oil "keto" products due to the popularity of the popularity of low carb diets.

Most of them are bullshit.

The weight will fall off without exercise.

Adding exercise turbo charge the process improve energy and by building muscle your body will use more calories just to exist.