[Mirioron]

I would recommend getting a variety of sources of information while staying very skeptical of any outlandish claims. However, the reason why diet is more important than exercise is that exercise doesn't burn many calories compared to how many calories you need for your body's upkeep during a day.[0]

Look at those numbers and keep in mind that a daily recommended caloric intake is at 2000 kcal. Now look at caloric values of food - carbs and protein are at around 4 kcal per gram and fat is 9 kcal per gram. Take pineapple juice for instance - it has around 60 kcal per 100 ml. If you drink 2 glasses of that (400ml) then that's already more than 10% of your daily calories. People often drink an entire liter per day though.

[0] https://www.health.harvard.edu/diet-and-weight-loss/calories...