Problem with this lazy, surface level comparison is that it never leads to anything good.
What are the factors causing these British holiday makers to be bigger compared to their European counterparts?
French smoke more, have more work life balance, they have more employee friendly policies, which gives you time for other things including cooking and exercising, they have better climate, and many other things. UK is also the most densely populated European country. So life is a bit more difficult than in Europe.
NHS is not on knees because of overweight people. It's due to bad government policies.
French are not passive when it comes to major government policy change. UK has a more keep calm, carry on approach. Look at the shit show Tory government has caused in the country in last 10 years. Be it handling of Corona Virus siruation or Brexit or economy. French would not be sitting calmly and carrying on.
People are working harder to get basic income. They are tired, so it is essy to go for processed meals at the end of a tiring day. Processed meals taste good, are addictive.
How about you vote better next time, care about the politics and economy of the country, focus on your weight and health and stop blaming people you know nothing more than a superficial observation of how they look.