I happened to catch this interesting documentary on BBC3 last week which followed a female model who ditched her fine dining and switched to low fat 'diet' foods for four weeks. Not only did she put on weight over the trial period, she also suffered a worrying loss of memory and concentration, fatigue, ravenous hunger, constipation and bloating. The scientists and nutritionists on the program put these symptoms down to lack of fibre, good fats and nutrients from the 'low fat' foods.
These 'low fat' alternatives are usually very low in nutritious value and often laced with sugar which in my opinion is worse than the fat that it is replacing. Give me a nice plate of roasted fresh fish and grilled veggies anytime - so much more nutritious, less expensive and just as quick to prepare!