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Research Suggests A Low Carb Diet Just Two Days A Week Resulted In More Weight Loss Than Restricting Calories All Week

Published on September 20, 2012,

With thanks to a blog post on the site Fat Head for flagging up an article from last year looking at a study investigating the impact of intermittent carbohydrate restriction on both weight loss and health benefits.  Amazingly the study (amongst women considered to be at high risk of breast cancer) found that participants who restricted carbs to 50g two times a week but ate without restrictions the rest of the week lost more weight and gained bigger improvements on key health markers than participants who ate a restricted 1500 calorie diet every day. A third group who both restricted carbs to 50g and and and ate only 650 calories on the two restricted days showed similar results to those who just restricted carbs on two days but not calories. This is from the original article in Diabetes In Control…

Adhering to a strict, low-carbohydrate diet two days per week led to greater reductions in weight and insulin levels when compared with standard daily dieting….

Can you diet for just two days a week? You might be able to drop more weight if you cut back on carbs just two days a week.

British researchers found that women who essentially gave up carbs for two days and ate normally the rest of the time dropped about 9 pounds on average, as compared to the 5 pounds lost by women who cut back to around 1,500 calories every day, according to a new report presented at the CTRC-AACR San Antonio Breast Cancer Symposium.

The study’s lead author Michelle Harvie, a research dietician at the Genesis Prevention Center at the University Hospital in South Manchester, England stated that, “We came up with the idea of an intermittent low-carb diet because it enables people to still have foods that are very satiating.” “Also, there’s a lot of evidence from other studies showing that restricting carbohydrates has the same effect as restricting energy.”

Harvie and her colleagues were spurred to find a diet that would be easier for women to follow because research has shown that obesity and the changes it causes in the body increase the risk for breast cancer. “We know from our research in animal models that losing weight has the potential for reducing breast cancer risk,” Harvie said.

The researchers followed 88 women for four months. All the women were at high risk for breast cancer based on their family histories. One third of the women were put on a Mediterranean-type diet that restricted calories to about 1,500 per day. A second group was told to eat normally most of the time, but two days a week to cut carbs and also calories to about 650 on those two days. The third group was also to cut carbs two days a week, but there was no calorie restriction on those days.

At the end of four weeks women in both of the intermittent dieting groups had lost more weight — about 9 pounds — than the women who ate low calorie meals every day of the week — about 5 pounds.

Women in the intermittent dieting groups also had better improvement than daily dieters in the levels of hormones — insulin and leptin — that have been linked with breast cancer risk, Harvie said. And, yes, this is something you can try at home, Harvie said. You just need to dramatically cut back carbohydrates two days a week and try to eat sensibly the rest of the time, she added.

What that means, Harvie said, is that you can eat protein and healthy fats on the two low carb days, but skip bread, pasta, root vegetables like potatoes, carrots and parsnips to get to the 50g limit. The diet allows for one piece of fruit on the low carb days. Other foods on the menu include: nuts and green, leafy vegetables, peppers, mushrooms, tomatoes, broccoli, eggplant and cauliflower.

Presented at the CTRC-AACR San Antonio Breast Cancer Symposium Nov. 2011

More at: Low Carbs for Just Two Days a Week Spurs Weight Loss

The results appear fascinating because they suggest not only that low carb diets appear more effective than calorie counting but also the possibility that an intermittent approach to food restriction is, in its own right, powerful. Intuitively this makes sense because the body will be unable to adapt to a consistent change. It also ties in with the recent articles (‘Related articles’ below) than consider, respectively, an intermittent fasting approach and the potential benefits of an occasional high carb day on an otherwise low carb diet.

High-carb diet tied to possible breast cancer risk for some

Published on August 2, 2012,

Reuters has a report on a new study suggesting older women who eat a lot of starchy and sweet carbohydrates may be at increased risk of a less common but deadlier form of breast cancer.

The findings, from a study of nearly 335,000 European women, do not prove that your French fries, sweets and white bread contribute to breast cancer.

But they do hint at a potential factor in a little understood form of breast cancer, according to a researcher not involved in the work.

Specifically, the study found a connection between high “glycemic load” and breast cancers that lack receptors for the female sex hormone estrogen.

A high glycemic load essentially means a diet heavy in foods that cause a rapid spike in blood sugar. The usual culprits include processed foods made from white flour, potatoes and sweets. A sweet, juicy piece of fruit can also raise blood sugar quickly. But since fruits are low in calories, they don’t contribute as much to your diet’s glycemic load.

So-called estrogen receptor (ER)-negative tumors account for about one-quarter of breast cancers. They typically have a poorer prognosis than ER-positive cancers because they tend to grow faster and are not sensitive to hormone-based therapies.

In this study, postmenopausal women whose diets were very high in glycemic load had a 36-percent higher risk of ER-negative breast cancer, compared with women whose diets had the lightest load.

In general, a diet with a high glycemic load is not a particularly healthy one, noted Christina Clarke, a research scientist at the Cancer Prevention Institute of California in Fremont, and a consulting assistant professor at Stanford University.

“These types of diets have been associated with many negative health outcomes,” said Clarke, who was not involved in the study.

So although the current findings do not prove cause-and-effect, they can give women another reason to make healthier diet choices, according to Clarke.

Lead researcher Isabelle Romieu, of the International Agency for Research on Cancer in Lyon, France, did not respond to an email request for an interview.

From a scientific standpoint, Clarke said the results are interesting because so little is known about what causes ER-negative breast cancers. Most breast tumors – the ER-positive ones – have their growth fueled by estrogen.

“We really don’t know anything about what causes (ER-negative) tumors,” Clarke said. “This study gives us a really important clue for future research.”

Diets with a high glycemic load are associated with a bigger secretion of insulin, a hormone that regulates blood sugar. High insulin levels, in turn, have been linked to certain cancers, possibly because insulin helps tumors grow.

The current findings hint at a role for “insulin pathways” in ER-negative breast cancer, according to Clarke. “But there’s definitely more work that needs to be done,” she said.

The findings, which appear in the American Journal of Clinical Nutrition, are based on a long-running European study on nutrition factors and cancer risk.

Of nearly 335,000 women in the study, 11,576 developed breast cancer over a dozen years. Overall, there was no link between breast cancer risk and glycemic load – estimated from diet questionnaires the women completed at the study’s start.

But the picture changed when the researchers focused on postmenopausal women with ER-negative cancer. Among women in the top 20 percent for glycemic load, there were 158 cases of breast cancer, versus 111 cases in the bottom 20 percent.

When breast tumors also lacked receptors for the hormone progesterone, the gap was a bit more pronounced.

Still, the numbers “weren’t huge,” Clarke noted. And there are many other factors that could be different between those groups of women, although the study did account for some of them, including weight, exercise habits, calorie intake and smoking.

Clarke pointed out that there is no single factor in any woman’s risk of breast cancer. But, she said, the findings offer more incentive to eat a balanced diet that limits refined carbs in favor of healthier fare – like lean protein, vegetables, “good” fats and high-fiber grains.

“Really, you want to avoid these (high glycemic load) diets anyway,” Clarke said.

More at: High-carb diet tied to breast cancer risk for some

Original source: American Journal of Clinical Nutrition, online July 3, 2012.

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