Cutting dietary fat reduces body fat more than cutting carbs

In a recent study, restricting dietary fat led to body fat loss at a rate 68 percent higher than cutting the same number of carbohydrate calories when adults with obesity ate strictly controlled diets. Carb restriction lowered production of the fat-regulating hormone insulin and increased fat burning as expected, whereas fat restriction had no observed changes in insulin production or fat burning. The research was conducted at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. Results were published August 13 in Cell Metabolism.

"Compared to the reduced-fat diet, the reduced-carb diet was particularly effective at lowering insulin secretion and increasing fat burning, resulting in significant body fat loss," said Kevin Hall, Ph.D., NIDDK senior investigator and lead study author. "But interestingly, study participants lost even more body fat during the fat-restricted diet, as it resulted in a greater imbalance between the fat eaten and fat burned. These findings counter the theory that body fat loss necessarily requires decreasing insulin, thereby increasing the release of stored fat from fat tissue and increasing the amount of fat burned by the body."

The researchers studied 19 non-diabetic men and women with obesity in the Metabolic Clinical Research Unit at the NIH Clinical Center in Bethesda, Maryland. Participants stayed in the unit 24 hours per day for two extended visits, eating the same food and doing the same activities. For the first five days of each visit they ate a baseline balanced diet. Then for six days, they were fed diets containing 30 percent fewer calories, achieved by cutting either only total carbs or total fat from the baseline diet, while eating the same amount of protein. They switched diets during the second visit.

The researchers had previously simulated the study with a math model of human metabolism, whose body fat predictions matched the data later collected in the study. When simulating what might happen over longer periods, the model predicted relatively small differences in body fat loss with widely varying ratios of carbs to fat. Those results suggest the body may eventually minimize differences in body fat loss when diets have the same number of calories. More research is needed to assess the physiological effects of fat and carb reduction in the long term.

"This NIH study provides invaluable evidence on how different types of calories affect metabolism and body composition," said NIDDK Director Griffin P. Rodgers, M.D. "The more we learn about the complicated topic of weight loss, the better we can find ways to help people manage their health."

More than two-thirds of American adults are overweight or obese. Maintaining a healthy weight can help prevent complications related to overweight and obesity such as heart disease, type 2 diabetes and certain types of cancer, some of the leading causes of preventable death.

"Our data tell us that when it comes to body fat loss, not all diet calories are exactly equal," Hall said. "But the real world is more complicated than a research lab, and if you have obesity and want to lose weight, it may be more important to consider which type of diet you'll be most likely to stick to over time."

Statins should be viewed as a double-edged sword

Statins' success in reducing atherosclerosis-related events has elevated the medications to wonder-drug status, with some researchers advocating for their wider use as a preemptive therapy for cardiovascular disease. Using statins, however, can have side effects, including memory loss, muscle problems and increased diabetes risk. A new study in the American Journal of Physiology -- Cell Physiology explains why statins are more beneficial in some cases than others and highlights the importance of weighing individual risk when considering statins as a preventive measure.

Atherosclerosis develops when plaques build up inside blood vessels, which can lead to heart attack, stroke and death. Statins lower the risk by blocking cholesterol production in the liver, reducing a person's "bad" cholesterol.

The immune cells macrophages play a major role in plaque formation and rupture in atherosclerosis. Macrophages ingest fat deposits along the blood vessel wall and attract more macrophages, other cells and inflammation-related proteins to the injury site. The enhanced inflammation builds up the plaque within the vessel wall and further narrows the artery. Macrophages also release enzymes that weaken the fibrous cap that separates the plaque from the blood flow, increasing the likelihood that the plaque breaks open. Plaque ruptures lead to blood clots that result in strokes and heart attacks.

Macrophages primarily develop from stem cells that reside in the bone marrow. In a previous study, the research team from Tulane University School of Medicine observed that macrophages can also develop from mesenchymal stem cells (MSCs), which are found throughout the body. While bone marrow stem cells mainly become blood cells, MSCs can become all cell types, including bone, cartilage, muscle cells and macrophages.

In this study, the Tulane research team found that long-term statin use prevented MSCs from turning into macrophages, which could decrease inflammation and improve plaque stability in patients with cardiovascular disease. However, statins also prevented MSCs from becoming bone and cartilage cells. Statins increased aging and death rate of MSCs and reduced DNA repair abilities of MSCs. "While the effect on macrophage differentiation explains the beneficial side of statins, their impact on other biologic properties of stem cells provides a novel explanation for their adverse clinical effects," the researchers wrote.

The risks of statin use are associated with statins' negative effects on stem cell function, according to the researchers. Statin therapy benefits individuals with atherosclerosis, but because of its effects on stem cells, it may not be appropriate as a preventive measure for those who do not have cardiovascular disease, the researchers wrote.

Moderate physical activity associated with lower risk of heart failure in men

Men who participated in moderate amounts of physical activity, particularly walking and bicycling, were associated with a lower risk of future heart failure compared to those with lower and higher levels of activity. However, recent active behavior may play a more important role than past physical activity, according to a study published today in the Journal of the American College of Cardiology: Heart Failure.

Heart failure is a condition where the heart is unable to pump as much blood as the body needs. Around 23 million people suffer from heart failure globally, including almost 6 million in the United States. On average, people have a 20 percent lifetime risk for developing heart failure.

Researchers followed 33,012 men from the Cohort of Swedish Men from 1998 until 2012--or first event of heart failure--to determine if physical activity was associated with heart failure risk. Overall, men who had the lowest and highest levels of physical activity had a higher risk of heart failure, 47 percent and 51 percent respectively, than men with a median level. When analyzing the different types of physical activity, walking or bicycling for 20 minutes per day was associated with the largest risk reduction.

When enrolling in the study, participants from two counties in Sweden completed a questionnaire about their level of activity at work, home, walking or bicycling, and exercise in the year prior at an average of 60 years old and retrospectively at 30 years old. Researchers assigned each type of physical activity an intensity score and determined walking or bicycling just 20 minutes per day was associated with a 21 percent lower risk of heart failure and accounted for the largest difference in heart failure free survival. Of the men diagnosed with heart failure during the course of study, those who had engaged in at least 20 minutes per day in walking or bicycling were approximately eight months older compared to heart failure cases who had engaged in less than 20 minutes per day of walking or bicycling.

While researchers acknowledged the use of self-reported physical activity meant levels were possibly misclassified, the questions on physical activity in the Cohort of Swedish Men were validated in a prior study using a sub-population of the participants.

Upon analyzing the different types of activities, certain types of physical activity were associated with reduced risk of heart failure such as walking and bicycling or exercising more than one hour per week. Meanwhile occupation, household work and physical inactivity were not significantly associated with heart failure development. Researchers also found that men who were active at 30 years old but were inactive at the time of study enrollment did not have a decreased risk of heart failure.

"Because participants in the study cohort had also provided information about their physical activity at age 30, as well as at the time of enrollment around age 60, we were able to examine the long-term impacts of physical activity on heart failure," said Andrea Bellavia, M.Sc., of the Karolinska Institutet in Stockholm and one of the study authors. "We found that recent activity may be more important for heart failure protection than past physical activity levels. The first incidence of heart failure in men was also later for those who actively walked or bicycled 20 minutes each day."

While the study suggests both low and high levels of physical activity, compared to more moderate levels, could increase the risk of heart failure in men, study authors cautioned that the link between physical activity and heart disease is not fully understood. Heavy physical activity, such as long distance running, or manual labor may put stress on the body, which in turn has adverse effects on the heart.

"The U-shaped relationship between exercise levels and the likelihood of subsequent heart failure is a unique finding and will stimulate further research in the important field of prevention," said Christopher O'Connor, M.D., editor-in-chief of the Journal of the American College of Cardiology: Heart Failure.

In an accompanying editorial, Steven J. Keteyian, Ph.D., and Clinton A. Brawner, Ph.D., of the Division of Cardiovascular Medicine at Henry Ford Hospital in Detroit, wrote, "We are reminded that we still know relatively little about how variations in physical activity and exercise 'dose' might impact disease onset."

According to Keteyian and Brawner, the paradoxical nature of the findings that risk of heart failure development actually increases for those reporting high levels of physical activity leads them to ask, "How much exercise it too much?" However, they also said they believe the study findings reinforce the "message that a moderate level of total physical activity is an important behavioral strategy" in both the treatment and prevention of heart failure.

Testerone study shows benefits

A Veterans Affairs database study of more than 83,000 patients found that men whose low testosterone was restored to normal through gels, patches, or injections had a lower risk of heart attack, stroke, or death from any cause, versus similar men who were not treated.

The study also found that men who were treated but did not attain normal levels did not see the same benefits as those whose levels did reach normal. The study was published online Aug. 6, 2015, in the European Heart Journal.

The findings may sway the ongoing debate over testosterone therapy's benefits and risks, especially for the heart. Studies over the past few years have yielded mixed results, although part of that might stem from differing patient populations and research methods.

For example, the new VA study excluded men with a history of heart attacks or strokes, although it did include those with existing heart disease. A much-cited VA database study that was published in JAMA in 2013 looked specifically at men with coronary artery disease; about 20 percent of the total study group of around 8,700 men had suffered a prior heart attack.

So far, the medical community lacks results from any definitive clinical trial that might provide clear guidance. Meanwhile, the Food and Drug Administration issued guidance earlier in 2015 advising clinicians about the over-use of testosterone therapy, and pointing to a possible increased risk of heart attack and stroke.

The new VA study is likely to draw attention because of its large size and relatively long follow-up period.

Dr. Rajat Barua, the paper's corresponding author, says the study is also noteworthy because of its finding that administering the right dose is critical: Treating "low T" but not restoring levels to normal doesn't appear to impart much benefit, at least in terms of cardiovascular risk. Testosterone isn't prescribed with the goal of improving heart health, but that is a consideration in many cases.

"It is the first study to demonstrate that significant benefit is observed only if the dose is adequate to normalize the total testosterone levels," Barua and his coauthors wrote. "Patients who failed to achieve the therapeutic range after testosterone replacement therapy did not see a reduction in [heart attack] or stroke and had significantly less benefit on mortality."

Barua is with the Kansas City (Mo.) VA Medical Center. He's also an assistant professor of medicine at the University of Kansas.

The study team looked at national data on more than 83,000 men with documented low testosterone, all age 50 or above, who received care in VA between 1999 and 2014.

The researchers divided the men into three clinical groups: those who were treated to the point where their total testosterone levels returned to normal (Group 1); those who were treated but without reaching normal (Group 2); and those who were untreated and remained at low levels (Group 3).

Importantly, all three groups were "propensity matched" so the comparisons would be between men with similar health profiles. The researchers took into account a wide array of factors that might affect cardiovascular and overall risk. They included, for example, age, body mass index, various chronic diseases, LDL cholesterol levels, and the use of aspirin, beta blockers, and statins.

The average follow-up across the groups ranged from 4.6 to 6.2 years.

The sharpest contrast emerged between Group 1 (those who were treated and attained normal levels) and Group 3 (those whose low testosterone went untreated). The treated men were 56 percent less likely to die during the follow-up period, 24 percent less likely to suffer a heart attack, and 36 percent less likely to have a stroke.

The differences between Group 1 and Group 2 (those who were treated but did not attain normal levels) were similar but less pronounced.

Little difference emerged between Groups 2 and 3, except for a slight benefit in survival for those who were treated.

Barua and colleagues say they don't know the exact reasons for testosterone's apparent benefits for the heart and overall survival. "The mechanisms for these effects remain speculative," they write. Possible explanations, they say, could involve body fat, insulin sensitivity, lipids, blood platelets, inflammation, or other biological pathways. More research is needed, they say, to clarify how testosterone affects the cardiovascular system.

While the new study results do seem to advocate for testosterone replacement therapy, Barua stresses the need for "appropriate screening, selection, dosing, and follow-up of patients to maximize the benefit of testosterone therapy."

The authors also caution that "off-label" use remains a concern. In other words, doctors should not write a prescription simply because an older man is complaining of symptoms such as low energy and low sex drive. According to the FDA, "Testosterone products are FDA-approved only for use in men who lack or have low testosterone levels in conjunction with an associated medical condition.

Examples of these conditions include failure of the testicles to produce testosterone because of reasons such as genetic problems or chemotherapy. ... None of the FDA-approved testosterone products are approved for use in men with low testosterone levels who lack an associated medical condition."

Saturated fats are not associated with an increased risk of death, heart disease, stroke, or Type 2 diabetes.

A study led by researchers at McMaster University has found that while trans fats are associated with greater risk of death and coronary heart disease, saturated fats are not associated with an increased risk of death, heart disease, stroke, or Type 2 diabetes.

The findings were published today by the British Medical Journal (BMJ). The lead author is Russell de Souza, an assistant professor in the Department of Clinical Epidemiology and Biostatistics with the Michael G. DeGroote School of Medicine.

"For years everyone has been advised to cut out fats. Trans fats have no health benefits and pose a significant risk for heart disease, but the case for saturated fat is less clear," said de Souza.

"That said, we aren't advocating an increase of the allowance for saturated fats in dietary guidelines, as we don't see evidence that higher limits would be specifically beneficial to health."

Guidelines currently recommend that saturated fats are limited to less than 10 per cent, and trans fats to less than one per cent of energy, to reduce risk of heart disease and stroke.

Saturated fats come mainly from animal products, such as butter, cows' milk, meat, salmon and egg yolks, and some plant products such as chocolate and palm oils. Trans unsaturated fats (trans fats) are mainly produced industrially from plant oils (a process known as hydrogenation) for use in margarine, snack foods and packaged baked goods.

Contrary to prevailing dietary advice, a recent evidence review found no excess cardiovascular risk associated with intake of saturated fat. In contrast, research suggests that industrial trans fats may increase the risk of coronary heart disease.

To help clarify these controversies, de Souza and colleagues analysed the results of 50 observational studies assessing the association between saturated and/or trans fats and health outcomes in adults.
Study design and quality were taken into account to minimise bias, and the certainty of associations were assessed using a recognized scoring method developed at McMaster.

The team found no clear association between higher intake of saturated fats and death for any reason, coronary heart disease (CHD), cardiovascular disease (CVD), ischemic stroke or type 2 diabetes.

However, consumption of industrial trans fats was associated with a 34 per cent increase in death for any reason, a 28 per cent increased risk of CHD mortality, and a 21 per cent increase in the risk of CHD.

Inconsistencies in the studies analysed meant that the researchers could not confirm an association between trans fats and type 2 diabetes. And, they found no clear association between trans fats and ischemic stroke.

The researchers stress that their results are based on observational studies, so no definitive conclusions can be drawn about cause and effect. However, the authors write that their analysis "confirms the findings of five previous systematic reviews of saturated and trans fats and CHD."

De Souza, a registered dietitian, added that dietary guidelines for saturated and trans fatty acids "must carefully consider the effect of replacement foods.

"If we tell people to eat less saturated or trans fats, we need to offer a better choice. Unfortunately, in our review we were not able to find as much evidence as we would have liked for a best replacement choice, but ours and other studies suggest replacing foods high in these fats, such as high-fat or processed meats and donuts, with vegetable oils, nuts, and whole grains."

Little to no effect of testosterone on atherosclerosis, sexual function and quality of life in aging men

Testosterone sales have grown rapidly over the last decade, but few studies have examined the long-term effects of taking testosterone on cardiovascular health and other important outcomes. This week, investigators from Brigham and Women's Hospital (BWH) report the results of the Testosterone's Effects on Atherosclerosis Progression in Aging Men (TEAAM) trial in the Journal of the American Medical Association (JAMA). The three-year study finds that testosterone administration had no effect on the progression of hardening of the arteries in older men with low to low normal testosterone levels and did not significantly improve sexual function or health-related quality of life.

"The results of this trial suggest that testosterone should not be used indiscriminately by men," said corresponding author Shalender Bhasin, MD, director of BWH's Research Program in Men's Health: Aging and Metabolism and director of the Boston Claude D. Pepper Older Americans Independence Center at BWH. "We find that men with low and low normal testosterone are unlikely to derive benefits in terms of sexual function or quality of life, two reasons why men may seek testosterone therapy. And although we find that testosterone did not affect the rate of hardening of the arteries, we need long-term data from large trials to determine testosterone's effects on other major cardiovascular events."

Testosterone, a hormone primarily secreted by the testicles, plays a key role not only in male reproductive tissues but also in muscle growth, bone mass and body hair. As men get older, their testosterone levels naturally decline - on average by 1 percent a year after age 40. Previous studies that have aimed to examine rates of cardiovascular events in men taking testosterone have reported conflicting results but have raised concerns that testosterone therapy might increase a person's risk of a heart attack or stroke. Atherosclerosis, or the buildup of plaque in the arteries, is a critical risk factor for such cardiovascular events.

In the three-year, double-blind TEAAM trial, the research team enrolled more than 300 men over the age of 60 with total testosterone levels between 100-400 ng/dL (low to low normal range) and measured two indicators of atherosclerosis: calcium deposits in the arteries of the heart (coronary artery calcification) and the thickness of inner lining of the carotid arteries that supply blood to the brain (common carotid artery intima-media thickness). To measure secondary outcomes of sexual function and health-related quality of life, the research team had participants also completed a 15-item questionnaire. Participants applied a testosterone or placebo gel daily for three years.

"Our study has important implications for clinical practice, and for older men who are seeking testosterone therapy," said Bhasin. "Many men, as they get older, experience a decline in testosterone and in sexual function and vitality. But our study finds that taking testosterone, when levels are in the low to low normal range, may not improve sexual function or quality of life."

The TEAAM trial was designed to examine atherosclerosis progression and not cardiovascular events -- further studies will be needed to determine the cardiovascular safety of testosterone use in older men. The research team also notes that comparing patients using statins to those who are not could be another important direction for future studies.

Southern diet could raise your risk of heart attack

If your dinner plate often includes fried chicken, gravy-smothered liver, buttered rolls and sweet tea -- your heart may not find it so tasty. Eating a Southern-style diet is associated with an increased risk of heart disease, according to research published in Circulation, an American Heart Association journal.

In a large-scale study that explored the relationship between dietary patterns and heart disease risk, researchers found that people who regularly ate traditional Southern fare -- which they characterized as fried foods, fatty foods, eggs, processed meats, such as bacon and ham, organ meats like liver, and sugary drinks -- were at a higher risk for suffering a heart attack or heart-related death during the next 5.8 years. Previous research also links the Southern diet with increased stroke risk.

The study is one of the first to include a regionally and socioeconomically diverse population. Researchers compared the dietary habits of more than 17,000 white and African-American adults in different regions of the United States. After adjusting for a combination of demographic and lifestyle factors, along with energy intake, they found:

• People who most often ate foods conforming to the Southern dietary pattern had a 56 percent higher risk of heart disease compared to those who ate it less frequently.
• The highest consumers of the Southern diet tended to be male, African-American, those who had not graduated from high school or were residents of southern states (North Carolina, South Carolina, Georgia, Tennessee, Alabama, Mississippi, Arkansas and Louisiana.)

No other dietary pattern was associated with the risk of heart disease.

"Regardless of your gender, race, or where you live, if you frequently eat a Southern-style diet you should be aware of your risk of heart disease and try to make some gradual changes to your diet," said James M. Shikany, Dr.P.H. lead researcher and a nutritional epidemiologist at the University of Alabama at Birmingham's Division of Preventive Medicine. "Try cutting down the number of times you eat fried foods or processed meats from every day to three days a week as a start, and try substituting baked or grilled chicken or vegetable-based foods."

Researchers used data from participants in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study of white and African-American men and women aged 45 or older enrolled from 2003 to 2007. Participants were screened by telephone and then given an in-home physical exam and food frequency questionnaire that asked how often and how much, on average, they consumed the foods during the previous year.

Researchers grouped the types of foods the participants regularly ate into five dietary patterns: the "convenience" pattern was comprised mostly of pasta dishes, Mexican food, Chinese food, mixed dishes and pizza; the "plant-based" pattern which was mostly vegetables, fruits, cereal, beans, yogurt, poultry and fish; the "sweets" pattern which consisted of added sugars, desserts, chocolate, candy and sweetened breakfast foods; the "alcohol/salads" was characterized by beer, wine, liquor, green leafy vegetables, tomatoes and salad dressings, and the "Southern" pattern, which was an eating pattern that the researchers observed to a greater extent in the Southeastern United States, included added fats, fried food, eggs and egg dishes, organ meats, processed meats and sugar-sweetened beverages.

Every six months, the participants were interviewed via telephone about their general health status and hospitalizations for nearly six years. For this study, the researchers only included participants who had no known heart disease at the beginning of the study.