The “secret” of being able to eat as much as you want isn’t really a secret at all. It’s all about calorie density and food volume, or bulk.
Humans, on average eat about 2-2.5 pounds of food a day. Our stomach is roughly the size of two softballs. If we choose foods that are high volume (make us feel full) but low calorie density we can eat as much of them as we want because we will feel full LONG before we intake too many calories. If you ate 2 pounds of just beans you’d only get about 1200 calories. But trust me, you would feel full! The higher calorie density foods are easy to over eat because we don’t feel full before we’ve taken in 1000s of calories.
Any veggies, fruits, starches and legumes are going to make you feel full, give you all the nutrients you need AND allow you to reach and maintain your ideal body weight without ever feeling deprived. So eat up!