Not a pain at all
I'm a dietitian by trade, so I quite like talking this subject!
Nuts are naturally high in fat, but not all fats are created equal and it's important to remember that you do need to have some fat in your diet! Nuts are a great source of healthy fats, especially in their raw state, and are also highly nutritious for their vitamin and mineral content. Different nuts will give different ratios of fats, so eating a variety is the best thing to do. Personally, I love Brazil nuts (very crunchy - chocolate coated is my all time favourite snack
And excellent post-exercise due to the protein and carb content) and cashews (almost meaty in texture). Walnuts, almonds, peanuts, pistachios - whatever you like really. If you are concerned about fat in your diet, it might be worth noting that a diet rich in good fats is actually cardioprotective - you're less likely to suffer from high cholesterol, heart disease, high blood pressure, etc. That doesn't mean eat nothing but nuts - it's all about balance!
It's common for people to be wary of fats and sugars - the healthy eating message is everywhere! However - and a lot of people have trouble with this - the healthy eating message is intended for the general public, and you have to remember that the general public tend to be rather sedentary. Athletes, and people who engage in a lot of exercise, have different needs. That's not to say you shouldn't follow a healthy diet - being active doesn't mean you're completely protected from the risks of heart disease, diabetes, etc. But it does mean that you need to adapt to your own lifestyle. And given the high workload of cardio you describe, and the weight loss, it's evident that your diet isn't currently meeting your needs. If you need to get a few extra calories from 'unhealthy' foods, then so be it. They tend to be at their most unhealthy when they make up a large proportion of your diet, and that wouldn't be the case for yourself, then there's not too much to worry about
Quite frankly, the risks of being underweight are greater than those of being having a bit of chocolate now and again.
As for Marmite -
