Experts from the programme offer their advice on health, good food and weight loss - with more added each week.
Read Professor Ashley's reaction to the first episode. How did she feel when she first saw Si and Dave’s food dairy?
In this week's update, Professor Ashley explains why fatty foods - like a cooked breakfast - are the ones we crave the most...
Are there healthy takeaway options? Professor Ashley takes us through the dishes to try, and those to avoid.
Professor Ashley explains which alcoholic drinks are the most calorific in her final update - and offers a few final words of wisdom.
"My main areas of research are on the prevention and treatment of obesity, with a focus on prevention of obesity in children."
Read Professor Roy's first update on Si and Dave. Discover more about body fat and some of the instruments he uses to measure it.
Is breakfast really the most important meal of the day? Professor Roy gives his verdict in this week's update.
Professor Roy discusses the joy and benefits of cycling in his update for the third week of Si and Dave's challenge.
Read about the importance of the 'trouser test' and some parting hints and tips in Professor Roy's last update.
"The series is very close to my heart - all the techniques used to motivate and measure Si and Dave are the same ones used in my research."