I now live in Australie, and it is fascinating to compare. In France, go into any playground in the morning, not a single kid will have anything to eat. They play then go home for a real lunch , not a sandwich. Sandwiches are for travel and car journey when you don't have access to food. No parents gives a sandwich for lunch in a home , it is breakfast, la tartine..... Here food is everywhere, all day long. Well, can't really call it food, it is mainly cochonnerie.
Tbh, neither kind of national diet sounds particularly healthy. And as official statistics show half of all French people are overweight with 1 in 5, of total population, being obese, the end result shows that it's not necessarily great. There is no one special way to eat healthily apart from focussing on your nutritional needs and keeping your intake of processed foods, especially processed sugars, low enough that it doesn't mess up your relationship with your appetite. I know for me that I went through a period or real sugar addiction where I constantly mistook sugar cravings for hunger. When I quit processed sugar, I learned to understand when I was actually hungry again, and how I ate changed drastically.
The ultimate key to honed, toned legs is to lose any excess bodyweight. Even with a BMI in the healthy range, you may still be carrying too much fat for you personally. The second is exercise to build muscle in the legs, running, cycling, long distance skating, dance etc will all help with this. And the third is to build flexibility and strength in a range of motion. Exercises designed for ballet dancers really are great for the latter.
And lastly, even with well built, strong flexible legs and a diet that keeps away excess body fat, you have to accept that you have a natural bodyshape and your legs can only ever look their best within that shape. I have short legs, wide hips and naturally strong, muscular thighs. I'll never have long, honed, gazelle like legs. Unless I ever end up severely under-weight, I will always have "thick" thighs and even fairly pronounced calf muscles. So it's important to know what's natural for your body to look like at it's best and pursue that, rather than have ideal that isn't right for your shape.