You are what you eat...or is there more to it than that?

A recent article by Emma John in The Observer, (Sunday 19 September 2010) makes a pretty convincing argument that it is what we eat more than what we do that accounts for our weight. In a list entitled: 'Snack attack: how long it takes to burn off 10 favourite foods' the following examples are given:

• 'One portion of Tesco lasagne (560 cal): 45 minutes of spinning
• One slice of Domino's pepperoni pizza (198 cal): 45 minutes of swimming
• Morrisons' chocolate-chip muffin (476 cal): 58 minutes of climbing
• Packet of Walkers cheese and onion crisps (184 cal): 35 minutes of frisbee
• Subway tuna wrap (310 cal): 1 hour and 10 minutes of body pump
• Bacon sandwich on white bread (430 cal): 58 minutes of football
• Coffee Republic ham and cheese toastie (436 cal): 1 hour and 30 minutes of netball
• Granny Smith apple (62 cal): 15 minutes of weightlifting
• M&S hot cross bun (159 cal): 20 minutes of skipping
• Mars bar (280 cal): 50 minutes of aqua aerobics'

This is quite a convincing argument and ought to make those with shares in gyms more than a little anxious about their investments.  On the other hand there are some systemic factors not addressed.  Weight loss and body image are, after all, not mere biological issues.  Exercise produces endorphins which in turn can be linked to moods and predispositions to depression.  The manners of living that are conserved in eating, drinking and exercise are also likely to be significant.  I delight in the 'slow eating' in France when staying with friends and the mix of foods - but find it hard to recreate the same features in my own home in another cultural context. The creation of 24 hour cities in the UK and Australia has escalated binge drinking and other unintended consequences.  We also know far too little about how different bodies react to foods in terms of the feelings of satiation and emptiness. Add to this how little we know about the microbial ecologies of our digestive system and how this may interact with different foods! All in all there is much still to be learnt about this topic - some of the wasted resources used on poorly designed gym activities and dieting fads would be better spent in a systemic national well-being strategy!