Perhaps the biggest nutritional mistake people make is not eating enough foods in their natural state and replacing them with processed foods. Take apple juice as an example. Even the simple act of removing the pulp to make apple juice detracts from its value for both health and weight loss. A medium size apple contains just 72 calories, and over 3 grams of fiber, while 8 fl oz of apple juice contains 120 calories and no fiber at all. And we're just talking about pure, "healthy" apple juice.
Natural foods are also nutritious and contain much of what is good for us, including vitamins and minerals, fiber, the cancer-fighting antioxidants found in fruits and vegetables, and the sustained energy provided by whole grains and complex carbohydrates. They reduce our risk of heart disease, diabetes, and cancer.
Eat More "Low Energy Dense" Food
Recent work by Rolls et al.has shown that modifying meals to increase the amounts of fruits and vegetables, which are generally not particularly energy dense, increases satiety and leads people to select meals with a lower total calorie content. Additionally, when only a portion of the total diet was replaced with lower-energy-dense foods, the calorie loss was still substantial. However, they have also found that instructing subjects to increase the fruits and vegetables in their diet was not sufficient for weight loss to occur, unless the added fruits and vegetables also displaced high-energy-dense foods(1). Low energy density and low GI tend to cluster, because both categories favor increased fiber, lowered added sugars, and increased whole grains
The Fiber Connection
Because natural fruits, vegetables and whole grains are high in complex carbohydrates and fiber, they are absorbed slowly and satisfy our feelings of hunger. Heavily processed foods, on the other hand, are not only low in nutritional value, but they don't make us feel satisfied so we eat more of them. They are made from refined ingredients that are so tasteless they require large amounts of salt, sugar, fat, and high-priced advertising to make them attractive.
The Lean Protein Connection
Adding low fat, lean protein to each meal will lower the glycemic index rating of any carbohydrate. Why? Adding protein causes a carb meal to be absorbed more slowly. This reduces blood sugar levels which in turn keeps insulin levels low. This has many health benefits. If we eat a diet that contains too many high GI carbs (carbs that are rapidly converted into blood glucose) we force our body to respond by releasing equally large amounts of insulin into our bloodstream to cope with the glucose. Over time this excessively high level of insulin can cause the "insulin-receptors" in our cells to become less sensitive to insulin. When cells become less sensitive to the effects of insulin, they accept less glucose, so more glucose than usual remains in the bloodstream. The pancreas must then over-compensate by working harder and releasing even more insulin. The combination of insulin-insensitivity and insulin over-production typically leads to one of two results:
- Either, the pancreas gets worn out and insulin production slows down to abnormally low levels. Result? We develop type 2 diabetes. (About 30 percent of cases)
- Or, the insulin-resistant patient doesn't develop diabetes (because the pancreas continues to produce sufficient insulin) but, instead, contracts hyperinsulinism (abnormally high levels of insulin in the blood), which can cause chronic obesity as well as high blood pressure, high levels of triglycerides, low HDL (good) cholesterol, heart disease, and possibly some cancers.
Therefore adding protein to carbohydrate meals will lower the overall GI value, and as a result keep blood sugar levels lower and allow the pancreas to work less hard. Meals that are absorbed slower also have the added benefit of satisfying our feelings of hunger and making us feel full, resulting in less calorie consumption.
As briefly touched on above, diets high in sugar and refined carbohydrates like bread, pasta, cereal, and other mainly "low-fat" processed foods increase your body's production of insulin. When insulin is at high levels in the body, the food you eat can get readily converted into body fat, in the form of triglycerides (to top it off, high triglyceride levels in the body are one of the greatest risk factors for heart disease). Eating these foods also tend to leave you less satisfied than those that contain adequate fat levels; so you eat more and get hungrier sooner.
Restrict processed/refined carbohydrates, such as high-sugar foods, white flour foods such as breads, pasta, etc. Instead consume nutrient-dense, unprocessed foods. By doing so you will feel full sooner , feel more full overall, and consume less calories as a result. Therefore eating more healthy foods will help you lose weight.
People who eat healthy, mostly unprocessed foods, including fruit, vegetables, whole grains, legumes (lentils, dry beans and peas), and limited amounts of lean animal protein (reduced-fat dairy, fish, chicken, and lean cuts of other meats), often find that they can eat as much as they want without gaining weight.
(1) Rolls, BJ, Ello-Martin, JA, Tohill, BC. (2004) What can intervention studies tell us about the relationship between fruit and vegetable consumption and weight management? Nutr Rev. 62,1-17 [Medline]