Are you suspicious of carbs? Looking at a low-carb diet to lose weight? Dietitian Nicole Senior explains that not all carbs are equal and how some may even help you lose weight.
We know that cakes, biscuits and soft white bread are high in carbs. And so are hot chips, potato crisps and flaky pastries. If you find that these foods are de-railing your good health intentions, it seems logical to think that quitting carbs might be the answer to your health woes.
You might have also heard so-called fitness gurus talk about how you can ‘burn fat’ and shed weight fast if you deprive your body of carbohydrates. Are they telling the truth? Well, yes and no. And we’ll explain why in a minute.
The most important thing to understand is that not all carbs are created equal, and that the right kinds of carbohydrates can help you lose weight, keep it off and ensure you get longer-lasting satisfaction from your meals. We’ll show you which ones these are. But first, let’s go back to nutrition basics.
What are carbohydrates?
Carbohydrates are one of the main nutrients in our diet; the others being protein and fat. There are three main types of carbohydrates found in food: sugars, starches, and fibre. Your body needs all three forms of carbs to function properly.
Sugars and starches are broken down by the body into glucose (blood sugar) to be used as energy.
And fibre is the part of food that is not broken down. It helps you to feel full and can help you maintain a healthy weight.
Why do we need carbs?
So we can enjoy freshly baked bread! Seriously though, carbs are our body’s basic fuel — like petrol in a car. When digested, carbs are broken down into the simplest form of sugar, called glucose, which as mentioned before, the body uses as energy.
Glucose is the main source of fuel for the brain and muscles, which explains the brain fog, low mood and fatigue that people often experience when following very low-carb diets.
Carbs and weight
Restricting kilojoules results in weight loss, regardless of whether you cut carbs, fat or protein. In fact, when diets low in carbs were compared to diets that weren’t low in carbs, the amount of weight lost was the same, according to some studies.
Cakes, biscuits and soft drinks are high in carbs. But they’re also high in fat, sugar and, importantly, kilojoules. So, when people lose weight when they cut these foods from their diet, they often wrongly attribute the weight loss to being on a low-carb diet.
But there are other high-carb foods which don’t carry the extra fat and sugar, such as lentils, grains and starchy veg. Instead, they’re loaded with fibre and a raft of vitamins and minerals. So, clearly, not all high-carb foods are the same.
Bread cops a bad rap, too, but white, fluffy bread is very different to dense, wholegrain loaves with visible seeds and grains. Similarly, a puffed rice breakfast cereal is high in carbs, but so is a bowl of nutritious muesli. There’s good evidence to show that people who eat lots of whole grains weigh less than those who eat very few. So, it’s not cutting all carbs which will help you lose weight — it’s the type of carb that you cut that will do the trick.
Low carbs vs slow carbs
Just as you want to put the best quality fuel in your car for peak performance, you also want to fuel your body with high-quality carbohydrates. These include whole grains like barley and quinoa, high-fibre cereals, beans and legumes, and fruit and starchy vegetables, like sweet potato.
These foods are referred to as slow carbs because our body digests them slowly and they provide long-lasting energy. They are also called low-GI foods. The Glycaemic Index (GI) measures the rate at which carbs are digested. High-GI foods (think white bread or fried chips) are digested quickly, giving you a rapid surge in energy only to then drop down quickly.
Choosing low-GI carbs keeps you full for longer, which helps with weight control. Low-GI carbohydrates also help to manage blood glucose and insulin levels which, in the long term, helps to reduce your risk of developing type 2 diabetes and heart disease.
How many carbs do we eat?
A healthy diet needs about half its energy to come from good quality carbs. Most of us aren’t overdoing the amount of carbs we eat, but we could do better on quality. The last national dietary survey (2011–12) found on average that Australians eat one-third of their daily kilojoules from foods like pies, cakes, biscuits and pastries, which are high in carbs but low on nutrients.
Foods, not carbs
Talking about food only in terms of its carbohydrate content is missing the forest for the trees. Dietary guidelines around the world are getting back to basics and talking about food, and so should we.
There’s no need to ditch all carbs to lose weight and be healthy, just choose better quality carbs. This table shows you the best, the ok and the worst ones.
Dense grainy bread, breads with seeds, oats and soy, grain wraps
Oats, barley, quinoa, freekeh
Bulgur/burghul (cracked wheat)
Wholemeal pasta, wholemeal couscous
Doongara rice, wild rice, low-GI brown rice, brown basmati
Wholegrain breakfast cereals, muesli
Pumpkin, sweet potato, taro, parsnip
Pulses and legumes (lentils, chickpeas, kidney beans, baked beans, soy beans)
Mung bean noodles
Lower-GI potato varieties (e.g. Carisma, Nicola)
Sweet corn, popcorn
Milk and yoghurt
Eat smaller portions or less often
Regular wholemeal or white bread, high-fibre white bread, crumpets, English muffins
White rice, rice pasta, rice milk
Low-fibre breakfast cereals (e.g. corn flakes, puffed rice)
Rice crackers, rice cakes, corn cakes
Why is white rice and brown bread in the ‘eat less often’ section?
White and wholemeal bread, and white rice, all have a high GI because of the type of starch in the rice, and the fine milling of the bread flour to achieve a smooth texture. There is more fibre in wholegrain bread and brown rice so they’re a better choice.
NOTE: Brands may differ. To find out the glycaemic index of foods, check out glycemicindex.com
Do low-carb diets really work?
Yes, but so does any other diet where energy (kilojoules/calories) is restricted.
A low-carb diet is usually defined as being below 100g of carbs a day (or around a third of what national guidelines recommend).
When your body isn’t getting enough energy from carbs, it turns to burning primarily fat for fuel. The by-products of doing this smell like acetone, and explains the bad breath often experienced while on low-carb diets.
The success of any diet relies on how well you can stick to it and how healthy it is. And low-carb diets don’t rate well on these. Following a very low-carb diet can mean missing out on vital nutrients as well as increasing other health risks.