Many people cut back on carbohydrates in an effort to either loose weight, or for other health reasons. But how does this effect our health in reality?
There are three different forms of carbohydrates found in food. Some food contains more than one type of carbohydrate.
Sugars are simple carbohydrates that can either occur naturally in certain food (e.g. fruit and fruit juice, sugar and honey, dairy) or may be added to products (sweetened cereals, cakes, jam, etc.) and provide a quick source of energy. This energy often wears off soon after ingestion as blood glucose levels drop rapidly.
Starch is a more complex carbohydrate that comes from plants and provide a more steady release of energy to the body. Examples include whole grains (brown rice, rye, barley, etc) , legumes (beans, peas and lentils), and starchy vegetables (corn, sweet potato, butternut).
Fibre is present in plant-based food and doesn’t provide energy as it is not absorbed by the body. It keeps our bowels regular, reduce cholesterol levels, and help maintain blood glucose levels. Food rich in fibre includes fruit and vegetables, legumes, whole grains, nuts and seeds.
Low carbohyrate diets
Not all low carbohydrate diets are created equal. These diets vary in the amount of carbohydrates, protein and fats. They also differ in the type of foods permitted. Some of these diets promote healthier choices (such as legumes, olive oil, nuts, fish, etc), whereas other low carbohydrate diets just focus on the restriction of carbohydrates overall and may exclude food containing valuable nutrients and cause a high intake of saturated fats.
The recommended minimum requirements for adults is 130g per day of which most is used to fuel the brain. The World Health Organisation recommends 45 – 65% of calories from carbohydrates to meet our energy and nutrient needs. This is equal to 225 – 325g of carbohydrates per day if based on a 2000 calorie diet.
There are different “catagories” of carbohydrate-restricted diets:
Ketogenic / Very Low Carbohydrate diet (VLCD)
These diets contain 20 – 50g carbohydrates or 10% of calories from carbohydrates. It avoids most other foods containing carbohydrates such as milk-products, legumes, grains, fruit and starchy vegetables. And includes larger amounts of protein and fats and may focus on foods high in saturated fat (such as processed meat and butter) and low in fibre. The Atkins diet is an example and contains less than 50g of carbohydrate in some of its phases.
Diet This diet is slightly higher in carbohydrates (at least 130g per day, or more than 26% of calories from carbohydrates) and includes a greater variety of carbohydrate-containing foods such as fruit, vegetables, legumes, and dairy. Therefore, it allows for more nutrients and fibre that is usually absent in the VLCD.
Moderate carbohydrate diet
A diet moderate in carbohydrates allows for at least 130g of carbohydrates (more than 26% calories from carbohydrates), and includes a greater variety of foods that contain carbohydrates from vegetables, fruit, legumes, dairy, and grain products. The Zone diet” is a moderate carbohydrate diet with 200g of carbohydrates or 40% of calories from carbohydrates.
Low Carbohydrate Diets and Weight Loss
Any diet that exclude or reduce any food group is usually also calorie restricted, which may help with weight-loss in the short-term. This is often because you are reducing portion sizes and restricting energy-dense desserts, cakes, sweet treats, sugar-containing cold drinks etc. Everyone can benefit from reducing sugar or foods with added sugar and low in essential nutrients.
The long-term effects of very low carbohydrate diets are not yet confirmed, but achieving a nutritionally adequate and healthy dietary pattern becomes problematic with extreme low carb diets that emphasise high fat intake from predominantly animal foods and restrict and eliminate many nutrient- and fibre-rich foods. Legumes, vegetables, fruit, grains, and low fat dairy contain nutrients and fibre that may reduce the risk of certain diseases such as heart disease, diabetes, and bowel cancer.
Research shows that over the long-term , people have the same weight loss on a calorie-reduced diet, regardless whether it is low or moderate in carbohydrates. What is important is to choose a dietary pattern you can stick to. Lifelong changes in eating and physical activity are needed to reach and maintain a healthy weight.
Consult your dietitian if you are considering a low carbohydrate diet. A dietitian can help you build an eating pattern that will meet your nutritional needs and help you reach your goals while reducing your health risk.
Thank you to Melissa Ludick – FEMINA HEALTH dietitian for the contribution.