Why do nutritionists' recommendations differ?

Or Why is the science of nutrition so confusing, and healthy eating is not as simple as we would like?

Is intermittent or continuous weight loss better?

Many slimming people often choose not the most effective method to achieve their goals. That is, they do not really understand how better it would be: to lose weight with short breaks, or to be "on a diet" with a kcal deficiency all the time?