In-laws keep giving my toddler sweets and junk despite me saying no

From my experience, grandparents show love through food, so fighting it head-on rarely works. What worked for me was giving my MIL a 'job' with rules, like she's in charge of the fruit and the one small treat after dinner, so she still feels involved but within limits. I also let the paediatrician tell her during a visit, somehow doctor's words carry more weight than daughter-in-law's. Get your husband to be the one who talks to his own mum, that reduces the tension a lot. Pick your battles, occasional sweets won't ruin your child, but set clear non-negotiables like no coffee and no sweets before meals.

We went through the same drama with my parents. What helped was consistency and framing it as the child's health, not criticism of grandma. I'd say 'doctor said his teeth and tummy still developing, cannot yet' rather than 'don't spoil him'. We also kept a small stash of healthier snacks at their house so when the urge to feed comes, there's an approved option ready. For the tantrums, it does pass once the pattern breaks, stay firm for two weeks and it settles. Most importantly your husband must back you up in front of his mum. If it's really affecting nutrition, a quick chat with the paediatrician or a clinic nurse helps set the record straight.