The Latest on Carbs: Are They Healthier Than We Once Thought?
Carbohydrates (aka carbs) are the enemy – or so we have been led to believe. Plenty of research says that low-carb diets are better than other diets, such as low-fat diets, leading us to wonder if pasta and potatoes are best left for “cheat” days. Carbohydrates cover a broad range of foods, including fruits, vegetables, grains, and dairy products, and not all carbs are the same. The type and quantity of carbohydrates in our diet is what’s important. There are a number of myths concerning carbohydrates, so we’re here to help you distinguish fact from fiction.
The Latest Research on Carbs
A meta-analysis published in the British Journal of Nutrition looked at 11 randomized controlled trials and found that compared to participants on low-fat diets, participants on low-carb diets experienced greater reductions in body weight and triglycerides but greater increases in HDL (good) cholesterol and LDL (bad) cholesterol. The authors concluded that the beneficial changes of low-carb diets must be weighed against the possible detrimental effects of increased LDL cholesterol.http://www.ncbi.nlm.nih.gov/pubmed/26768850
Low-fat diets often restrict fat intake to 30 percent (this isn’t much of a restriction because average fat intake is roughly 30 to 35 percent). The average person’s carbohydrate intake is around 50 to 60 percent of their energy intake, so restricting that to around 20 percent naturally cuts calories. Another large, comprehensive study found evidence that low-fat diets were not necessarily better than any other diet. However, participants on a low-fat diet lost weight, as did those on low-carb diets. The people who restricted carbohydrate intake lost more, but this may have been due to the researchers defining “low fat” as comprising 30 percent of the diet or less.http://www.thelancet.com/journals/landia/article/PIIS2213-8587(15)00367-8/abstract
A recent study of 19 obese people found that calorie-controlled low-carb and low-fat diets actually led to equal amounts of lost body fat. Although the number of people in this study was very low, the study was carried out under strict parameters. For two weeks, participants were kept in a metabolic lab and scientists provided them with a precisely controlled diet. One group got a low-carb diet that reduced their total calories by 30 percent. Another group received a low-fat diet that also reduced their total calories by 30 percent. Then, after a few weeks of rest, the two groups switched diets. Both groups lost the same amount of body fat. The low-carb group lost three pounds more, but this was from losing water and not fat. This study suggests that carb restriction is not necessary to lose weight. More studies like this with larger sample sizes are necessary before we can deduce an optimal dieting pattern.http://www.cell.com/cell-metabolism/abstract/S1550-4131(15)00350-2
Bear in mind that cutting out carbohydrates and replacing those calories with fats and higher fat sources of protein can increase saturated fat intake, which may increase heart disease risk.http://www.cochrane.org/CD011737/VASC_effect-of-cutting-down-on-the-saturated-fat-we-eat-on-our-risk-of-heart-disease If you choose to cut back on carbs, it is important – as it is with any dietary change – to ensure that all your other health needs are met so you aren’t doing more harm than good.
Types of Carbohydrates
Carbohydrates are one of three macronutrients (nutrients that form a large part of our diet) found in food. The other two are fat and protein. Hardly any foods contain just one macronutrient, and most contain a combination of carbohydrates, fats, and proteins in varying amounts.http://www.nhs.uk/livewell/loseweight/pages/the-truth-about-carbs.aspx
There are three different types of carbohydrates: sugar, starch, and fiber.
Sugar is found naturally in some foods, including fruit, fruit juices, milk (lactose), and vegetables. Other forms of sugar can be added to food and drinks, such as baked goods and soda, or added during the cooking or baking process at home; one common form is table sugar. Honey, agave nectar, and maple syrup, although natural, still fall under the added sugar bracket. In the United States, added sugars (i.e., ones that come from sources other than dairy products and whole fruit) should be limited to a maximum of 10 percent of your energy intake. For an adult consuming a diet of 2000 calories, this equals between 100 and 200 calories of added sugars, which is around five to 10 teaspoons of sugar per day as a maximum. Higher intakes of sugar are associated with obesity and cavities.
Starch is made up of many sugar units bonded together. It is found in plant-derived foods. Starchy foods, such as bread, rice, potatoes, pasta, and couscous, provide a slow, steady release of energy throughout the day, and they should be included at each mealtime.
Fiber is only found in foods that come from plants. Fiber helps keep our bowels healthy, and some types of fiber may help lower cholesterol. Research shows that high-fiber diets are associated with lower risks of cardiovascular disease, type 2 diabetes, and bowel cancer. Good sources of fiber include whole-grain bread, whole-wheat pasta, pulses such as beans and lentils, root vegetables, nuts, seeds, oats, and fruit.https://www.bda.uk.com/foodfacts/Carbs.pdf
How Carbs Affect the Body
Carbohydrates should be the body’s main source of energy, accounting for 40 to 50 percent of your energy intake. Carbs are broken down into glucose (sugar) before being absorbed into the bloodstream. From there, the glucose enters the body’s cells with the help of insulin, which is released from the pancreas. Glucose is helps make energy that fuels everything we do, from for a run to breathing. Unused glucose can be converted to glycogen, which is found in the liver and muscles. If unused, glucose can be converted to fat for the long-term storage of energy. Carbs are particularly important in people who are physically active. Some carbohydrate is stored in the body; however, there is a limited supply. During exercise, these stores are depleted. The best way to replenish carb stores is to eat a carbohydrate-rich snack or meal as soon as possible after training. A post-workout snack or meal should also contain protein because it helps replenish your stores more quickly. For example, you can choose to eat breakfast cereal with milk, a yogurt or fruit smoothie, or a stir-fry with rice or noodles. A diet that’s too low in carbs can lead to a lack of energy during exercise, early fatigue, and delayed recovery.
Carbohydrates also provide fiber and other important nutrients. Vegetables, pulses, whole-grain varieties of starchy foods, and potatoes eaten with their skins are all good sources of fiber. Though fiber is really important, most of us do not eat enough. Fiber can promote good bowel health and reduce the risk of constipation. Some forms of fiber have also been shown to reduce cholesterol levels. Healthy sources of carbs – such as whole-grain starchy foods, vegetables, fruits, legumes, and dairy products – are also an important source of nutrients including calcium, iron, and B vitamins.
Fruit, vegetables, pulses, and whole-grain starchy foods provide a wide range of vitamins and minerals as well as fiber to keep your bowels healthy and add bulk, which helps us feel full. To stay healthy, aim for an average intake of 30 grams of fiber a day.
Sweets, chocolates, and soft drinks with added sugar are usually high in sugar and calories, providing very few other nutrients. Try to limit the amount of sugary foods you eat and include healthier sources of carbohydrate in your diet instead.
Carbs and the Glycemic Index
Carbohydrate-containing foods affect blood sugar differently. The Glycemic Index (GI) is a measure of how quickly a food containing carbohydrate increases blood sugar. Foods with a lower GI cause smaller increases in blood sugar, and they are more likely to keep us feeling fuller for longer. Foods with a higher GI are more likely to increase blood sugar levels quickly, which leads to a rapid insulin release and blood sugar levels plummeting again after an hour or so. This is why having sugary cereal or white toast for breakfast can leave us feeling very hungry a couple of hours later. However, rolled oats, which have a lower GI, are more likely to keep you feeling full until lunch. There are limitations to using GI; it is measured per 50 grams of carbohydrate, and it is not based on the portion of food you would eat.
Glycemic Load (GL), on the other hand, considers the GI of a food and the available carbohydrate content in a usual serving. For example, carrots have a high GI but a low GL because GI is based on the increase caused by consuming 50 grams of carbohydrate from any food. Therefore, to get 50 grams of carbohydrate from carrots, you would need to eat around 700 grams of carrots (which is equivalent to around five large carrots) to cause your blood sugar to rise. Because the typical serving of carrots is much smaller, about 80 grams, this vegetable can be considered low GL; therefore, it can and should be part of a healthy diet. There’s also no need to eat carbohydrates on their own. Adding a fat and/or protein can slow digestion and the speed at which glucose gets into the bloodstream. For example, when you eat a baked potato, you may add baked beans to it; they contain protein and thereby slow the rate at which glucose increases your blood sugar.
Above all else, quantity is one of the main factors affecting whether carbohydrates promote weight gain or inhibit weight loss. Take a typical pasta dish. It often features an oversized portion of pasta, barely any vegetables, maybe a creamy sauce, and no other protein. In comparison to a recommended portion size of 150 grams of cooked pasta (approximately the size of a tennis ball), restaurants’ pasta servings (and sometimes at-home portions) are enormous. Carbs aren’t always a no-no food. But when you do eat them, consider your portion size and balance a snack or meal with healthy fats and protein.
Every individual has different tastes and ideas of what constitutes acceptable, achievable, sustainable lifestyle changes. Most people benefit from an increased fruit and vegetable intake, reduced alcohol intake, cooking from scratch, and relying less on processed foods and junk foods. Lowering fat intake or carbohydrate intake may help you lose weight if that’s the goal. One method may suit a person more than the other, which is fine as long as you also meet micronutrient needs and feel like the changes are sustainable.
Low-carbohydrate diets can be more motivating at first because of an initial substantial weight loss (from loss of water stored in glycogen). While fad diets may seem exciting, they can be hard to sustain. There are no quick fixes; you have to put in the work to reap the rewards.