¿Qué es el índice glucémico?
Cuando tomamos cualquier alimento rico en glúcidos, los niveles de glucosa en sangre se incrementan progresivamente según se digieren y asimilan los almidones y azúcares que contienen. La velocidad a la que se digieren y asimilan los diferentes alimentos depende del tipo de nutrientes que los componen, de la cantidad de fibra presente y de la composición del resto de alimentos presentes en el estómago e intestino durante la digestión.
Estos aspectos se valoran a través del índice glucémico de un alimento. Dicho índice es la relación entre el área de la curva de la absorción de la ingesta de 50 gr. de glucosa pura a lo largo del tiempo, con la obtenida al ingerir la misma cantidad de ese alimento.
High, Medium and Low GI Foods
One of the Internet’s most comprehensive lists of foods with their glycemic index. If you are following the GI or South Beach diet you should aim to include more foods with a low glycemic index in your diet. Your body will digest these foods slowly leaving you feeling full for longer and allowing you to eat less calories without feeling hungry. Adding a low GI food to a meal will lower the glycemic index of the whole meal. You can find meals that include low GI foods in our recipe section.
If you prefer the traffic light system used in the low G.I. diet book by Rick Gallop you can find the same data below arranged in red, yellow and green zones on our glycemic index chart.
El índice glucémico se determina en laboratorios bajo condiciones controladas. El proceso consiste en tomar cada poco tiempo muestras de sangre a una persona a la que se le ha hecho consumir soluciones de glucosa pura unas veces y el alimento en cuestión otras. A pesar de ser bastante complicado de determinar, su interpretación es muy sencilla: los índices elevados implican una rápida absorción, mientras que los índices bajos indican una absorción pausada.
The number listed next to each food is its glycemic index. This is a value obtained by monitoring a persons blood sugar after eating the food. The value can vary slightly from person to person and from one type or brand of food and another. A noticeable difference is the GI rating of Special-K which produced considerably different results in tests in the US and Australia, most likely resulting from different ingredients in each location. Despite this slight variation the index provide a good guide to which foods you should be eating and which foods to avoid.
The glycemic index range is as follows:
Cómo adelgazar con alimentos de bajo índice glucémico
Muy conocido por los diabéticos, el índice glucémico es un gran aliado de las dietas de adelgazar. Conozca mejor este factor, relacionado con la velocidad en que los alimentos son absorbidos por tu cuerpo, y la importancia que tiene para tu salud y buena forma.
Tabla de índices glucémicos de los principales alimentos
Sustituyendo los carbohidratos de bajo índice glucémico, especialmente en las meriendas o comidas aisladas, podemos mejorar la regulación del azúcar en sangre, reducir la secreción de insulina y ayudar a un programa de pérdida de peso. La tabla siguiente puede consultarse para elegir los alimentos de menor índice glucémico.
|80||Puré de patatas instantáneo|
|80||Maíz en copos|
|67||Sémola de trigo|
|59||Azúcar blanco (SACAROSA)|
|51||Patatas dulces (boniatos)|
|50||Espaguetis de harina refinada|
|42||Pan de centeno integral|
|42||Espaguetis de trigo integral|
A rápida absorção da glicose provoca uma queda acentuada do açúcar no sangue. Isso gera um estímulo para o cérebro, que responde com a fome. O resultado é que você come mais. “Se você come alimentos de alto IG e não queima calorias praticando exercícios, vai ganhar peso” , diz a nutricionista de Curitiba.
Por outro lado, os alimentos considerados de baixo índice glicêmico, cujo valor é próximo ou abaixo de 50, englobam arroz integral, a farinha integral, cereais, leguminosas (feijão, soja, lentilha e ervilha) e a maior parte das frutas. Ricos em fibras, eles retardam a absorção de açúcar e provocam uma metabolização lenta e gradual, garantindo saciedade por um período mais longo.
Mas isso não quer dizer que um cardápio de alto IG é um tremendo bandido. Após um treino longo de mais de uma hora de duração, por exemplo, a nutricionista Juliet explica que é fundamental comer alguma coisa que seja rapidamente metabolizada. “Isso é fundamental para dar energia ao organismo, que responde com a queima de gordura e poupa a queima de massa muscular. Desta forma, o metabolismo fica “esperto” para manter o peso. Com o abastecimento, ele entende que não precisa fazer estoque”, explica.
Na hora do lanchinho da tarde opte pelos itens com baixo IG. “Uma fruta com casa (rica em fibras, um iogurte ou três biscoitos integrais”, aconselha Juliet. Se você está há muitas horas sem comer e acha que pode compensar no chocolate, engana-se. O ciclo se repete. O açúcar do doce vai pedir mais insulina, ser rapidamente absorvido e a fome vai aparecer logo.
Alimentos com alto Índice Glicêmico
Gatorade – 91
Batata Assada – 85
Flocos de Milho ½ xícara – 84
Bolo de Arroz – 82
Batata-inglesa assada em microondas – 82
Bala jujuba – 80
Wafers de baunilha – 77
Creme de trigo instantâneo – 74
Mel – 73
Melancia 1 fatia média – 72
Pão branco 1 fatia média – 70
Pão de trigo integral 1 fatia média – 69
Farelo de Trigo – 69
Refrigerante Fanta – 68
Chocolate – 68
Cuscuz – 65
Açúcar – 65
Passas 1 colher de sopa – 64
Suco de Laranja 3/4 de copo – 57
Batata Cozida – 56
Arroz Branco – 56
Arroz Integral – 55
Pipoca – 55
Milho – 55
Batata-doce – 54
Banana bem madura 1 unidade – 52
Ervilhas verdes – 48
Feijões cozidos – 48
Arroz branco parboilizado – 47
Sopa de Lentilhas – 44
Laranja 1 unidade média – 43
Espaguete (sem molho) – 41
Pão de Centeio Integral 1 fatia – 41
Suco de Maçã (sem açúcar) 3/4 de copo – 41
Maçã 1 unidade média – 36
Pêra 1 unidade média – 36
Iogurte com frutas desnatado – 33
Grão-de-bico – 33
Leite desnatado – 32
Banana Verde 1 unidade média – 30
Lentilhas – 29
Feijões – 27
Leite Integral – 27
Frutose (açúcar da fruta) – 23
Carbohydrates, or carbs, are a type of nutrient in foods. The three basic forms are sugars, starches and fiber. When you eat or drink something with carbs, your body breaks down the sugars and starches into a type of sugar called glucose, the main source of energy for cells in your body. Fiber passes through your body undigested.
Two main hormones from your pancreas help regulate glucose in your bloodstream. The hormone insulin moves glucose from your blood into your cells. The hormone glucagon helps release glucose stored in your liver when your blood sugar (blood glucose) level is low. This process helps keep your body fueled and ensures a natural balance in blood glucose.
Different types of carbohydrates have properties that affect how quickly your body digests them and how quickly glucose enters your bloodstream.
Understanding GI values
There are various research methods for assigning a GI value to food. In general, the number is based on how much a food item raises blood glucose levels in healthy research participants compared with how much pure glucose raises their blood glucose. GI values are generally divided into three categories:
- Low GI: 1 to 55
- Medium GI: 56 to 69
- High GI: 70 and higher
For example, raw carrots have a GI value of 35. This means that if you eat enough carrots to consume 1.8 ounces (50 grams) of digestible carbohydrates (sugars and starches), your blood glucose level after eating the carrots will be 35 percent of the blood glucose level after eating 1.8 ounces (50 grams) of pure glucose.
Comparing these values, therefore, can help guide healthier food choices. For example, an English muffin made with white wheat flour has a GI value of 77. A whole-wheat English muffin has a GI value of 45.
Limitations of GI values
One limitation of GI values is that they don’t reflect the likely quantity you would eat of a particular food.
For example, watermelon has a GI value of 80, which would put it in the category of food to avoid. But watermelon has relatively few digestible carbohydrates in a typical serving. In other words, you have to eat a lot of watermelon to consume the standard test level of 1.8 ounces (50 grams) of digestible carbohydrates.
To address this problem, researchers have developed the idea of glycemic load (GL), a numerical value that indicates the change in blood glucose levels when you eat a typical serving of the food. For example, a 4.2-ounce (120-gram) serving of watermelon has a GL value of 5, which would identify it as a healthy food choice. For comparison, a 2.8-ounce (80-gram) serving of raw carrots has a GL value of 2.
Sydney University’s table of GI values also includes GL values. The values are generally grouped in the following manner:
- Low GL: 1 to 10
- Medium GL: 11 to 19
- High GL: 20 or more
A GI value tells us nothing about other nutritional information. For example, whole milk has a GI value of 31 and a GL value of 4 for a 1-cup (250-milliliter) serving. But because of its high fat content, whole milk is a poor choice for weight loss or weight control.
The published GI database is not an exhaustive list of foods, but a list of those foods that have been studied. Many healthy foods with low GI values are not in the database.
The GI value of any food item is affected by several factors, including how the food is prepared, how it is processed and what other foods are eaten at the same time.
GL in a nutshell
GL stands for Glycaemic Load. It’s a unit of measurement that tells you exactly what a particular food will do to your blood sugar. Foods with a high GL have a greater effect on your blood sugar, which isn’t desirable. Foods with a low GL encourage the body to burn fat, which is what we’re aiming for.
Keeping your blood sugar balanced is the concept at the heart of the low GL diet – sustainable weight loss will follow.
When your blood sugar level increases, the hormone insulin is released into the bloodstream to remove the glucose (sugar). Some glucose goes to the brain and muscles where it’s used as an energy fuel, but any excess goes to the liver where it’s turned into fat and stored, causing you to gain weight. Insulin is known as the fat-storing hormone.
The glycaemic load (GL) is based on the glycaemic index (GI). Put simply, the glycaemic index of a food tells you whether the carbohydrate in a food is fast or slow releasing (fast is bad, slow is good). What it doesn’t tell you is exactly how much of the food is carbohydrate. Glycaemic load on the other hand tells you both the type and amount of carbohydrate in the food and what that particular carbohydrate does to your blood sugar.
LOW GL WEIGHT LOSS IS MORE SUSTAINABLE THAN CONVENTIONAL DIETS
In a study published in the Canadian Journal of Cardiology, one group of people were put on a low GL diet and another group on a conventional low-fat, low-calorie diet (Canada’s Food Guide to Healthy Eating). Those following the low GL diet lost significantly more weight compared to those following the conventional low-fat, low-calorie diet (2.8 kg loss versus 0.2 kg gain). Weight loss was sustained over twelve months.
Study 1 – Cochrane Review
The latest scientific review of 6 studies looking at the effect of low GL diets on overweight people has shown that a low GL diet is more effective than any other diet for weight loss and improving overall health.
‘Overweight or obese people lost more weight on a low Glycemic Load diet and had more improvements in lipid profiles than those receiving conventional diets.’ The review compared the results of six well designed trials comparing low GL diets with conventional diets based on reducing calories. Other benefits were greater loss in body fat, reductions in bad ‘LDL’ cholesterol, and increase in good ‘HDL’ cholesterol.
The authors looked at 6 studies involving over 202 overweight people either on low GL or conventional calorie controlled diets. The diets ranged from 5 weeks to 6 months in length.
Body mass, total fat mass, BMI (Body Mass Index), total cholesterol and ‘bad’ LDL-cholesterol all decreased significantly more in the low GL groups than in the calorie controlled diets.
This study highlights the importance and effectiveness of following a low Glycemic Load diet, not only for weight loss but also for improving cardiovascular health.
Thirty-nine overweight or obese young adults aged 18 to 40 years followed a calorie-restricted diet, either low–GL or low-fat. Participants on the low–GL diet reported less hunger than those on the low-fat, low-cal diet.
Researchers at Kings College London University may have discovered why this is, and are presenting their findings today at the annual conference of the Society of Endocrinology. They fed volunteers a high or low GL meal and measured the release of a key hormone involved in appetite control, called gut hormone glucagon-like peptide 1 (GLP-1). GLP-1 levels went up by 20% after the low GL meal which is consistent with the reports of reduced appetite. These results show for the first time that eating a low GI meal increases GLP-1 production and suggests a physiological mechanism as to why a low GI meal makes you feel fuller than a high GI meal.
This is an important discovery as a natural desire to eat less is a great ally for those wanting to lose weight. One chef reported to me that he didn’t have a cut off switch as far as eating was concerned. “I could just eat and eat and would still be hungry throughout the day. After two months on your diet I now feel full and can leave food on the plate because I’m full. I’ve lost 38kg in six months and ten inches off my belly.”
Handy Tips to Reduce the GL
Having some handy tips and pointers when trying to lower your glycaemic load means that you need never get it wrong. Here’s a helpful list of things to remember.
Eat small or moderate portions of starchy foods such as bread, potatoes, pasta, and rice.
Include lots of low-GL fruit and vegetables at every meal. Aim for a minimum of five servings of fruit and veg per day. Lightly cook veggies for the minimum time or eat them raw. Fresh, frozen, or canned fruit and veg are all fine.
Make more of pulses including peas, beans, and lentils in soups, salads, and as a meal accompaniment instead of pasta or rice. Pulses, including dried or canned, count towards your five-a-day fruit and veg.
Always include a protein-rich food as part of your meal to reduce the GL. Chose from lean meat, fish, poultry, eggs, low-fat dairy foods, soya products, or quorn.
Adding acidic foods such as balsamic vinegar, lemon juice, vinaigrette, or pickles (for example, capers and gherkins) to your meal reduces the overall GL. Adding a little monounsaturated oil such as olive or rapeseed oil, or a little Parmesan cheese or
reduced-fat cream to recipes also reduces the GL.
Cut right down on highly refined snack foods such as sweets, crisps or corn chips, cakes, biscuits, and pastries made from white flour and sugar. Instead, choose nuts and seeds, or dried fruits such as apple rings or apricots. Instead of milk chocolate, snack on a couple of squares of dark chocolate with over 70 per cent cocoa solids.
Low-GL Seasonal Fruit and Vegetables
Good news: on the glycaemic load diet, you can indulge in hundreds of beautiful, scrumptious fruits and veggies. Check out this guide to what’s in season when.
|Spring||Rhubarb, grapes, limes, passion fruit, sharon fruit, lemons, grapefruit, avocados||Leeks, cabbage, watercress, new potatoes, spinach, aubergines, radishes, rocket, spring greens|
|Summer||Strawberries, raspberries, blueberries, redcurrants, blackcurrants, cherries, nectarines, melons||Asparagus, baby carrots, fresh peas, tomatoes, runner beans, lettuce, cucumber, courgettes, peppers mange tout|
|Autumn||Blackberries, apples pears, gooseberries, damsons, plums, elderberries, greengages, plums||Pumpkin, onions, fennel, wild mushrooms, squash, turnips, red cabbage, celeriac, swede|
|Winter||Satsumas, clementines, cranberries, mandarins, tangerines, pears, pomegranates||Brussels sprouts, chicory, cauliflower, kale, celery, mushrooms, purple sprouting broccoli|
The glycemic index range is as follows:
|Low GI = 55 or less
Medium GI = 56 – 69
High GI = 70 or more
Snacks & Sweet Foods