Savour the superfoods
In the morning, try sprinkling goji berries over your muesli to power you through the day. These little orange sparks of goodness hail from the Himalayas, where they are revered for contributing to the longevity of the locals. They also contain four unique polysaccharides (complex carbohydrates) that help control the body's immune system. They have a slightly peculiar aftertaste though, so beware of eating them on their own.
Come the mid-morning hunger pangs, treat yourself to a little raw chocolate. As long as you don't mix it with all the fattening sugar and hydrogenated vegetable oil found in commercial products, chocolate really can be good for you. Raw cacao (the bean from which chocolate originates) is a complex food, high in antioxidants, calcium and iron. It has, let's say, a unique flavour that is almost savoury, but it is crunchy as a peanut and filling. A handful of cacao "nibs" (shavings) will get you to the last bell. You should be able to get them at good wholefood shops.
For lunch, leave sandwiches behind and join the quinoa revolution. Bolivians use the native quinoa as a cheap and nutritious crop to pad out pretty much every meal. It's a more complete foodstuff than rice or wheat because it contains a more balanced set of amino acids.