If you have genuine concerns seek professional advice. Call the relevant HV team. If nothing happens as a result of that, call children's services.
The 'oh in this house we only have half a rice cake and a handful of seeds every three days modern life is so unhealthy and everyone is so fat' fetishisation of food restriction, with its links to class identity, will lead to children being hungry and malnourished. But hey, as long as you're not one of those skanks letting your baby have something processed or high in fat or containing sugar, it's all good, right? Starving has to be better than obesity!
People who have advised me to do any form of controlled crying over the years have had one polite "I don't support that, please don't talk to me about it" response, and if they have ignored that have been told to fuck off. That usually works.