When I talk to people about topics that contradict societal norms I try to put what is currently considered normal into context. Eating 3 meals a day and never going for periods of time without consuming/grazing is not normal for our bodies. It is something that has become more common over the last couple of thousand years, but it is not normal.
I don’t think we have evolved much from being hunter gatherers. As hunter gatherers our bodies are evolved to consume large amounts of food over the course of a few days or weeks and then go through times of little or no consumption. We have gotten rid of those times of no consumption and medical science hasn’t yet figured out how that affects our body processes.
Water fasting is natural. The constant grazing that is preached by governments and medical science does not work. That is why the diet industry is profitable. People are trying to find a pill to offset the bad diet habits they have been taught their entire lives.
There’s plenty of research out there to support your case, including books like The Longevity Diet by Valter Longo. You could also find a nutritionist in your area to support and monitor your fast, if that puts your wife at ease. If you’ve done your due diligence, you deserve the support of your wife. I also don’t think there’s anything wrong with being honest with your children and telling them you’re on a health-based fast, helping to reduce the stigma of the practice. Water fasting does not mean you’re anorexic, wreckless, or stupid, but health conscious.