Caloric restriction (CR) of 30%–50% increases the health span, lowers cholesterol, improves insulin sensitivity, delays the onset of aging and age-associated diseases, and improves metabolic health in most species. The problem with caloric restriction is that its extremely hard to people to follow a diet of this nature. Not many people can cut their calories by 40-50% and still be happy, in fact, its downright miserable. Even those with an iron clad will can’t maintain a 40% caloric reduction in the long term, and doing so can risk loss of bone mass, libido, and fertility. Now, new research in Cell Reports shows that, at least in mice, low protein, high carbohydrate diets can provide benefits similar to those obtained with calorie restriction. Whole grains and slow-release carbs, such as oatmeal and brown rice, for example, speed up the metabolism by stabilizing insulin levels. If you choose the right ones, researchers predict you’ll consistently boost your metabolism without gaining unnecessary weight.
Both caloric restriction (CR) and low-protein, high-carbohydrate (LPHC) ad-libitum
fed diets increase lifespan and improve metabolic parameters such as insulin, glucose, and blood lipids. Severe CR, however, is unsustainable for most people; therefore, it is important to determine whether manipulating macronutrient ratios in ad-libitum fed conditions can generate similar health outcomes. Researchers compared three diets varying in protein to carbohydrate ratio under both CR and ad libitum conditions. The rats were fed under conditions where they were placed on a diet and then allowed constant access to food. At the end of the eight week study, the low-protein, high-carbohydrate diet delivered similar benefits to caloric restriction in terms of levels of insulin, glucose, lipids, despite increased energy intake. Even though the mice on low-protein, high-carbohydrate diets ate more when food was always available, their metabolism was higher than that of mice on the calorie-restricted diet, and they did not gain more weight. Calorie restriction did not provide any additional benefits for low-protein, high-carbohydrate mice. The researchers reported that low-protein, high-carbohydrate diets under ad-libitum-fed conditions (i.e food always present) generate the metabolic benefits of caloric restriction diet without a 40% reduction in total caloric intake
American diets have a history of hating carbs, from Atkins low-carb diets, which restrict you to an average of 20 grams a day. Meanwhile, the Dietary Guidelines for Americans recommends that carbs should take up 45 to 65 percent of your daily total calories. Before you set out on this type a diet, more research is needed to determine how low-protein, high-carbohydrate diets affect long-term metabolic health and survival, as well as to what extent the type and quality of proteins and carbohydrates matter. “An important next step will be to determine exactly how specific amino acids, the building blocks of proteins, contribute to overall health span and lifespan,” says lead author Samantha Solon-Biet, also of the Charles Perkins Centre. If the study’s results apply to humans, adjusting protein and carbohydrate intake could lead to healthier aging in a more realistic manner than drastically cutting calories. “It still holds true that reducing food intake and body weight improves metabolic health and reduces the risk of diseases like type 2 diabetes, obesity, and fatty liver disease,” says Simpson. “However, according to these mouse data and emerging human research, it appears that including modest intakes of high-quality protein and plenty of healthy carbohydrates in the diet will be beneficial for health as we age.”
Solon-Biet et al. Dietary protein to carbohydrate ratio and caloric restriction: comparing metabolic outcomes in mice. Cell Reports, May 2015 DOI: 10.1016/j.celrep.2015.05.007