I generally prefer to eat at meal times rather than graze between meals.

我通常只在正餐的时候吃东西，而不是在两餐之间吃零食。

generally 通常、一般

prefer to do ... rather than do ... 更喜欢...，而不是...

at meal times 在正餐的时候

graze (on sth) 吃零食（代替正餐）

Around mid-morning I usually have some fruit and I eat a couple of cookies in the mid-afternoon.

我通常在早上九点十点吃一些水果，下午三四点吃两块饼干。

mid-morning 早上九点十点左右

mid-afternoon 下午三四点左右

a couple of ... 两个、两三个...

I think if people avoided snacking, they would be much healthier and less overweight.

我认为，如果人们不吃零食，他们会更加健康，（很多人）也不会像现在这样肥胖。

if people did ..., they would ... 注意虚拟语气

avoid sth/doing sth 避免、不去做...

snack v. 吃零食 snack on sth

overweight 太胖的、超重的

摘自微信公众号“杨帅英语口语”2022.06.28