Norman swan
Christmas is the season for good cheer, family rows and lots of guilt – mainly about what you eat. Healthy nutrition goes out the window until Boxing Day, when it comes galloping back as one of those resolutions you want to make for the upcoming year. So what should good resolutions look like when it comes to dieting?
Actually, I’m not waiting until Christmas. I’m already on a diet. I know, I know – dieting is passé. I should be permanently changing my intake and slowly lowering my weight in a sustainable way. The evidence – from Professor Boyd Swinburn of Deakin University in Melbourne and others who’ve mathematically modelled weight loss – is that when you modestly reduce your food intake, some of your excess weight comes off quickly. But it can take up to two years – yep you heard me right, two years – to hit the weight that matches your kilojoule intake.
The main reason appears to be that we metabolically adjust to the new intake. So, as our weight drops, we burn less energy to maintain it and the rate of weight loss slows down. Unfortunataely, this pace of weight loss requires the discipline and patience that only Tibetan monks on mountaintops possess.
But for transparency’s sake let me fill you in on my approach, which is loosely based on evidence.
First, I exercise fairly regularly – about an hour most days, a mix of aerobic exercise and weight training. It’s depressing how little food you burn by exercising, but when you’re controlling your portions and eating say, 8,300 kilojoules a day, an extra 1,600 kilojoules to play with can come in handy.
‘Slow cooking has got something going for it, as does slow eating…’
I also weigh myself daily, after I exercise. Now this is controversial. Swinburn and others have shown that if you mess up your intake while trying to lose weight, there is a lag of a few days before your body “catches up” and you see a weight gain. With this in mind – and accepting your weight fluctuates from day to day – daily weighing can be a good reminder of the task at hand.
Finally, I try not to change my diet on the weekends – fellow dieters, you know the temptation.
So now, what to eat.
The world is obsessed with single nutrients: carbs, protein, cholesterol, saturated fat, unsaturated fat, anti-oxidants, minerals, you name it. It’s a great way to sell books, but misguided. We didn’t evolve to swallow dietary supplements.
What counts is our eating pattern and lifestyle – they feed off each other. The evidence from long-lived populations is that their diets are low in saturated fat and high in vegetables. Consumption of red meat is low – protein is mostly provided by legumes, fish and poultry. Carbohydrates are not refined, and vinegar is used. In the West it’s the Mediterranean diet and in the East, with some variation, the traditional Japanese diet.
The cooking style, or “cuisine”, is important. Work done by Professor Kerin O’Dea and her colleagues at the University of South Australia has shown that slowly stewing red vegetables, such as peppers or tomatoes, in virgin olive oil releases far more potent anti-oxidants than you can get from a pill. It has to do with the lycopenes in the red colour.
There is also tantalising evidence that the vinegar in food products such as salad dressing is at least as important as the monounsaturated oil in the mix.
Japanese and Mediterranean cooking also tend to be less likely to burn food or turn it dark brown. Fascinating work at Melbourne’s Baker Institute has shown that the lovely brown caramelised sugars produced by roasting contain compounds called advanced-glycation end products, which are associated with free radical damage and premature tissue ageing. So the slow cooking movement has got something going for it, as does slow eating to keep your stomach and brain in sync, so that feelings of satiety have time to register. I also keep a food diary and try hard to be honest about portion size. You really need to know what 100 grams of meat looks like.
And what about alcohol, I hear you ask? Well, small amounts of alcohol do seem to help people at risk of coronary heart disease and don’t do any harm – unless, like me, your willpower to resist dessert is eroded by even the smallest glass of wine.
Breakfast is another battleground. There’s little doubt that children learn better if they have breakfast, but whether it’s essential for a healthy adult is moot. My anecdotal experience is that breakfast increases my hunger during the day and consequently my total energy intake. The evidence is mixed.
So think about your diet holistically, and how you prepare and eat it.
As for Christmas? Well, eat and be merry! And don’t think about getting back on the rails until Boxing Day.
