If you’ve ever tried to lose weight, it’s likely that cutting your calorie (or kilojoule) intake has been your first plan of attack.
But is all that painstaking scouring of food labels and number crunching actually effective? Well, yes and no.
The thing is, while the “calories in vs calories out” equation (ie, how much energy you consume compared to what you burn off) holds true, it’s only part of the weight-loss picture.
Where calorie counting fits in
While you may not need to track every single calorie you eat in order to lose weight, getting savvy about the calorie content of different foods can be useful.
“The majority of people don’t understand the calorie value of the foods they’re eating, or realise how high in calories some of those foods actually are,” says Julie Gilbert, accredited practising dietitian and spokesperson for the Dietitians Association of Australia.
According to Gilbert, understanding the energy value of different foods helps put them into perspective, so you can decide if they are a smart choice. For instance, a 53g Mars bar contains 244 calories – the equivalent of eating around three and a half slices of bread, or two and a half bananas.
Why the quality of calories matters
While the quantity of calories you consume will influence your weight, what’s arguably even more important is the quality of those calories.
“Not all calories are equal, in that we burn them at different rates and some calories make us feel fuller for longer,” says accredited practising dietitian Lyndi Cohen.
Protein, for instance, is a weight-loss winner, because it’s filling and also helps build muscle mass, which boosts our metabolic rate.
“It also takes more energy to burn protein than fat or carbohydrate,” says Cohen, “so if you consumed 100 calories of protein, about 30 of those calories would be used up digesting the protein.”
Fibre is similarly waistline-friendly because it’s filling and its structure means that not all of it is absorbed during digestion.
In contrast, refined carbohydrates (white bread and pasta, sugary cereals, lollies and biscuits) break down quickly, leading to a peak in insulin levels.
“When that happens, we don’t burn fat as effectively,” says Cohen, “and if we’re consistently having those foods it can put us at higher risk of insulin resistance, which makes it harder to lose weight.”
Adding to the case for focusing on healthy foods, a University of Florida study suggests that people whose diets were high in phytochemicals (indicating plenty of fresh produce) had lower BMIs and smaller waist circumferences.
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The (weight-loss) plot thickens
It turns out that what you eat isn’t the only factor swaying the scales. When you eat may also matter.
“Eating small, frequent meals can speed up the metabolism, although the effect is tiny,” says Cohen.
Another part of the weight-loss equation is sleep. “We know that a lack of sleep can throw ghrelin and leptin, the hormones that control hunger levels, out of whack,” says Gilbert.
Where you eat your meals is also important. “If you’ve got distractions like televisions or computers,” adds Gilbert, “they can impact how well your brain registers that you’ve eaten.”
Putting it all together
So, if calories matter but are only part of the picture, how should you approach weight loss?
It comes down to what works for you personally. “Calorie counting tends to suit people who like the ‘black and white’ approach of calculating what they’ve consumed,” says Gilbert. But it can be counterproductive in people prone to emotional eating, who may feel deprived and then over-eat.
A simpler way to keep your energy intake in check is to watch your portion sizes
. Easier still, opting for whole foods at every meal (think a filling combo of vegetables, lean protein, low-GI carbs and some good fat) is a foolproof way to shift the scales.
“Focusing on nutrient-dense foods,” says Cohen, “really is the secret to sustainable weight loss.”