Great Question. If you saw the queues outside Macdonalds here at lunch time, well, you would realise that the SAD diet is alive and well here in France.
I must just add a few things about the French diet, it is not just about cheese and wine. It is the WAY the french traditionally eat. It is a way of life here. All foodstuffs have their proper place and way of being eaten. Lunch is the main meal of the day, three courses are always eaten perhaps with an extra cheese course, wine is consumed by nearly every adult at lunch time as a digestive aid.
I believe that it is thus ATTITUDE towards food that is the key. OK sweets are eaten, bread is eaten, but the French believe in balance, a little of everything in moderation (soul food is just as important for our well-being) chocolate, tartes and pies, all made with pride and care. Many french people still have a smattering of knowledge of herbal remedies to aid digestion and they generally KNOW about food, REALLY know - from experience. I would definitely say it is the same in Italy, Spain etc.
Children are educated by their mothers and grandmothers in their own kitchens (which I believe is the factor common to all traditional diets) almost every garden outside of the city contains a vegetable patch which is used daily.
And it is this a way of life that is being encroached upon by the SAD diet, mainly through youth culture and fast food, but traditionalism is being valiantly upheld by the French as part of their heritage, because it is part of their identity as a nation, something the English or Americans lack......
There is a place for croissants and baguettes at the french table, but they are not eaten to excess, usually kept for breakfast. The french reject brown or rustic flour, saying that white flour is easier for the body to digest. Dairy is traditionally eaten raw and is still integral to meals here, giving the french a very high fat diet, in addition to other gourmet delights such as foie gras and pates, which are eaten regularly. Meat is always a very high standard, with the french preferring fattier cuts and organ meat leaving the leaner cuts for 'haute cuisine' which is more often found in restaurants than at the family table.
The French do not stress about their diets, they actually do not stress about much really (apart from such things as having to work a year longer before being able to draw a pension for example).
What I am trying to say is that perhaps the way of life, the diet represents and encompasses is just as important as what actually is part of that diet. Whether it is paleo, Mediterranean, French, whatever. Taken out of context - out of the way of life you need to live in order to REALLY appreciate it - it becomes just like any another diet to follow and stress about. OK, the SAD diet is obviously not good eaten in excess, but perhaps a range of high-quality food, lovingly prepared from the source, garden, local farmer etc (i.e. traditional) - which makes it automatically fat-rich and carb-poor, all eaten at its proper time and place, well-digested and eaten amongst those we love, stimulated with good conversation and in a relaxed atmosphere, is just as valid as another more 'politically correct' diet eaten on the run and with uncertainty.