How do you feel? Are you losing weight with those foods? Those aren't health-detrimental foods, but too much food period (and high carb-high fat at the same time) tend to impede weightloss.
There's nothing magical about sweet potatoes+ butter, but
1. Carbs in general suppress cortisol.
2. Carbs + fat combos (be it ice cream, milk chocolate, chocolate cake, fried potato chips, or sweet potatoes + butter) are hyper-palatable and hyper-addictive. This is why I tend to keep this particular food group low (healthy or not) when I'm trying to lose weight. It keeps food enjoyment down so I eat less.