Low Carbohydrate & Low Fat Diets the Same for Weight Loss

Many claims in lay media and scientific literature have been made regarding the superiority of a certain diet for inducing weight loss.  Two recent studies one published in the Journal of the American Medical Association and the second in Annals of Internal Medicine found that using either a low-carbohydrate or low-fat diet had the same end result. The best diet is that which works best for the dieter.

http://jama.jamanetwork.com/article.aspx?articleid=1900510

Johnston et al report in JAMA finding from their search of 6 electronic databases based on which they estimated the relative effectiveness of diets to affect weight and body mass index from baseline.  Weight loss and body mass index was determined at 6- and 12-month follow-up.

Among 59 eligible articles reporting 48 unique randomized trials that included 7286 individuals, the largest weight loss was associated with low-carbohydrate diets 8.73 kg at 6-month follow-up and 7.25 kg at 12-month follow-up and low-fat diets 7.99 kg at 6-month follow-up and 7.27 kg at 12-month follow-up. Weight loss differences between individual diets were minimal. For example, the Atkins diet resulted in a 1.71 kg greater weight loss than the Zone diet at 6-month follow-up.

They concluded significant weight loss was observed with both low-carbohydrate or low-fat diet. Weight loss differences between individual named diets were small.

http://annals.org/article.aspx?articleid=1900694

In the study by Bazzano et al published by the Annals of Internal Medicine, the effects of a low-carbohydrate diet compared with a low-fat diet of on body weight and cardiovascular risk factors was determined.

148 men and women without clinical cardiovascular disease and diabetes were placed on a low-carbohydrate (<40 g/d) or low-fat (<30% of daily energy intake from total fat [<7% saturated fat]) diet.

Data on weight, cardiovascular risk factors, and dietary composition were collected at 0, 3, 6, and 12 months.

Sixty participants (82%) in the low-fat group and 59 (79%) in the low-carbohydrate group completed the intervention. At 12 months, participants on the low-carbohydrate diet had greater decreases in weight (mean difference in change, −3.5 kg), fat mass (mean difference in change, −1.5%), ratio of total–high-density lipoprotein (HDL) cholesterol (mean difference in change, −0.44), and triglyceride level (mean difference in change, −0.16 mmol/L) and greater increases in HDL cholesterol level (mean difference in change, 0.18 mmol/L) than those on the low-fat diet.

They concluded low-carbohydrate diet was more effective for weight loss and cardiovascular risk factor reduction than the low-fat diet.

Based on these studies both low-carb and low-fat diets induced weight loss but there was not a sizable differences between the two. Finally, the branding of the diet did not have an impact on weight loss.

Cancers linked to Obesity

Obesity is a major contributor to the development of cancer.  According to the National Cancer Institute obesity is associated with increased risks for cancer of the esophagus, pancreas, colon and rectum, breast (after menopause), endometrium, kidney, thyroid, and gallbladder.

 

NHANES 2007-2008 survey found 68 percent of the U.S. adults age 20 years and older are overweight or obese and 17 percent of children and teens ages 2 to 19, are obese.  According to NCI Surveillance, Epidemiology, and End Results (SEER) data, it is estimated that in 2007 in the United States, about 34,000 new cases of cancer in men (4 percent) and 50,500 in women (7 percent) were due to obesity.

In 2003, Calle et al published in NEJM the results of a study of more than 900,000 healthy adults that were followed for 16 years.  The study authors concluded that excess fat could account for 14% of all deaths from cancer in men and 20% of those in women.

A recent study of 92,834 British women enrolled in a database for cancer screening, Fourkala et al reported in an article published in BMJ Open that women who go up a skirt size every decade between their 20s and their 60s are at increased risk of postmenopausal breast cancer.  They also found that “an increase of one size every 10 years led to a 33 percent rise in the risk of postmenopausal breast cancer, while an increase of two sizes per decade led to a 77 percent rise in risk.

Bhaskaran et al study of 5.2 million adults that was published in Lancet found that 166 955 individuals developed cancer and that body-mass index (BMI) was associated with 17 of 22 cancers.  Although the effects varied substantially by site, increase in BMI was roughly linearly associated with cancers of the uterus, gallbladder, kidney, cervix, and leukemia.  BMI increase was positively associated with liver, colon, ovarian, and postmenopausal breast cancers overall. They estimated inverse associations with prostate and premenopausal breast cancer risk, both overall and in non-smokers. By contrast, for lung and oral cavity cancer, they observed no association in non-smokers.  Assuming causality, 41% of uterine and 10% or more of gallbladder, kidney, liver, and colon cancers could be attributable to excess weight. They conclude that extra weight could contribute to more than 12,000 cases of cancer in the UK population every year.

Related Resources:

Physical Activity and Cancer

Energy balance: Weight and Obesity, PhysicalActivity, Diet

Obesity

A study by Ng et al reports on the prevalence of obesity in countries around the world.  Their research that was supported by Bill and Melinda Gates Foundation and published in Lancet, reviewed more than 1,700 studies covering 188 countries from 1980 to 2013.

The study found more than 2.1 billion individuals worldwide are overweight or obese, up from 857 million in 1980.  Also, obesity was estimated to have caused 3·4 million deaths, 3·9% of years of life lost, and 3·8% of disability-adjusted life-years worldwide in 2010.

They based their analysis on body-mass index (BMI) a measure of weight and height.  Individuals with a BMI of 30 or more are considered obese, while those a BMI of 25 to 29.9 are considered overweight, according to the U.S. National Institutes of Health.

Worldwide, the proportion of adults with a BMI of 25 or greater increased between 1980 and 2013 from 28·8% to 36·9% in men, and from 29·8% to 38·0% in women. In the US, 87 million individuals or 27.2% were obese according to study conducted in 2013 (Gallup). The prevalence of obesity has increased in children and adolescents worldwide.  In 2013, 23·8% of boys and 22·6% of girls were overweight or obese in developed countries, while in developing countries 12·9% of the boys and 13·4% of the girls were overweight or obese. One of the “most troubling” findings of the study is that the percentage of overweight or obese children and teenagers has increased by nearly 50 percent since 1980.   In the US alone, nearly 30 percent of the children and teens are either obese or overweight, up from 19 percent in 1980.

More than half of the world’s 671 million obese people live in the U.S., China, India, Russia, Brazil, Mexico, Egypt, Germany, Pakistan and Indonesia.  During the more than three decades studied, the largest increase in obesity rates were in Egypt, Saudi Arabia, Oman, Honduras and Bahrain for women and New Zealand, Bahrain, Kuwait, Saudi Arabia and the U.S. for men.  In adults, the estimated prevalence of obesity exceeded 50% in men in Tonga and in women in Kuwait, Kiribati, Federated States of Micronesia, Libya, Qatar, Tonga, and Samoa.  Since 2006, the increase in adult obesity in developed countries has slowed down.  

Because obesity can raise the risk of diabetes, osteoarthritis, heart disease and cancer, among other health-threatening conditions, strategies to correct it such increase physical activity, decrease of total caloric intake and selectivity the foods eaten are needed as obesity represents a major global health challenge.

Addendum:  A study based on review of the health records of 65,000 that was published in JAMAPediatrics (9/29/14) suggests infants and young children with repeated exposure to broad-spectrum antibiotics at ages 0-23 months are associated with childhood obesity. 

 

Ebola Outbreak

Ebola virus disease (EVD) also known as Ebola hemorrhagic fever is a severe illness, with a fatality rate of up to 90%. The infection is due to one of the five viruses in the family Filoviridaeis that are transmitted by direct contact with the blood, body fluids and tissues of infected animals or people.  In 1976, Peter Piot, a Belgian doctor travelled to the Congolese rainforest to find out why many people were dying from an unknown and terrifying disease.  Before departing he had observed a large worm like virus under an electron microscope, in a blood sample from a nun, who had died from a mysterious illness. It was the epidemiologic analysis in the field and the electron microscope finding that he and his associates made brought them to the conclusion they were dealing with a new virus they named after the nearby Ebola River.

When EVD outbreak occurs those at higher risk of infection are health workers, family members and others in close contact with sick people and deceased patients. 

Ebola virus disease outbreaks can devastate families and communities, but the infection can be controlled through the use of recommended protective measures in clinics and hospitals, at community gatherings, or at home.  The Ministries of Health of the affected countries and the World Health Organization (WHO) have reported an outbreak of Ebola in several Guinean, Liberian and Sierra Leone districts.  As of today 1,323 people have been infected and 729 have died, 339 in Guinea, 233 in Sierra Leone and 156 in Liberia, and 1 in Nigeria this is the largest outbreak of EVD in history. In Sierra Leone, Dr. Umar Khan, 39, the doctor who led the fight against Ebola, died from the disease.  His death follows that of prominent Liberian doctor Samuel Brisbane.  The transmission is usually thru close contact and not thru the air as in flu or measles. Because the EVD is spreading rapidly in Africa, and the world is inter-connected by air, public health officials are issuing warnings to health care workers to consider the Ebola virus when encountering travelers with flu-like symptoms from the affected countries in West Africa.  One such patient with Ebola boarded a flight in Liberia, had stopovers in Ghana, and Togo, and arrived in Nigeria, where he died days later. While experts say, it is unlikely he infected others, there are questions whether Ebola could become an epidemic to be spread by international air travel.  The fact that an infected person who may have been obviously ill managed to board a plane has stoked fears that other travelers could carry the disease to still more countries.  As a result, health officials in the affected countries are monitoring people for signs of infection before allowing them to board departing flights.  Also, travellers at airports in the affected countries will have to wash their hands with disinfectant and have their temperatures checked.  As EVD is one world’s most virulent diseases West African governments sought to control the spread of the virus, with Liberia recently closing its borders, while keeping the airport in Monrovia open with all travelers coming in and out tested for the virus.  On July 31, 2014 Sierra Leone declared a public health emergency and had security forces quarantine the epicenters of the outbreak in the east of the country.  Two airlines, Asky and Arik Air, have ceased flying to Liberia and Sierra Leone.

While the Center for Disease Control (CDC) said that “the risk of Ebola spreading to the United States was low,” it “nevertheless issued a Level 2 health alert, advising U.S. doctors and healthcare workers to check patients’ travel histories to identify those who might have recently traveled to West Africa.” In addition, the CDC “urged physicians to learn the symptoms of Ebola.”  EVD symptoms may appear anywhere from 2 to 21 days after exposure though 8-10 days is most common.  They typically include, fever, headache, joint and muscle aches, weakness, stomach pain, vomiting, diarrhea, lack of appetite, rash, red eyes, chest pain, cough, difficulty breathing and swallowing and bleeding inside or outside the body.  Severely ill patients require intensive hospital care, isolation and protective measures for those coming in contact with them.

Update:  On September 18, 2014 the United Nations Security Council issued the following statement: Determining that the “unprecedented extent” of the Ebola outbreak in Africa constituted a threat to international peace and security, the Security Council this afternoon called on Member States to respond urgently to the crisis and to refrain from isolating the affected countries.

Update:  On September 30, 2014 the CDC announced a patient with suspicious symptoms just back from West Africa was diagnosed with Ebola.  He was hospitalized at Texas Health Presbyterian Hospital in Dallas.  He is the first confirmed case with the disease in the U.S.

Update: On October 12, a nurse in Dallas, in the team that treated Thomas Duncan the Liberian man who died of Ebola on October 8, tested positive for the disease, officials in the Centers for Disease Control said.  It is not clear how she became infected despite wearing protective gear.  The news of her infection stoked fears among health care workers across the country.