Trouble is, that most people still think that 'low-fat' is the healthy option.
Low-fat means that the tasty, unctuous fat is removed, but loads of chemicals, sweeteners, binders and gum is put in. In no universe should this be the healthy food. Leave teh fat in, take the sugars out.
We have been told for decades that Fat is BAD, high fibre is good; eat pasta, brown bread, low-fat spreads, and not much else. And what's happened? We've all got fatter.
A lunchbox with protein like eggs, chicken or ham, yoghurt (FF), fruit and water is perfect. Slow-release energy, keeps you going for hours. Sugars and their replacements give you a sugar high for 2 hours, then you need something else, you crave sugar, your blood-sugars need another spike...
Cut the wheat (bloating) and the sugars, go for decent, non-mucked about food; that is the healthiest.