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Low-Fat and Low-Carbohydrate Diets

healthy foods

1. Please introduce yourself to the readers (how you started in the profession, education, credentials, experience, etc.).

My name is Tian Hu. I received my MD at Tongji Medical College in 2008 and Master of Science in Public Health at Penn State University in 2010. I entered Tulane University and began my full-time PhD in 2010 and worked with Dr. Lydia Bazzano in nutritional epidemiology. I have more than 4-year experience in research on the low-carbohydrate diet.

2. You recently published an article the differences between a low fat and low carbohydrate diet. Are we certain of anything in the literature regarding diets for weight loss and cardiovascular disease?

While low-fat diets have been recommended for weight loss and cardiovascular risk factor reduction for a long time, among women when this was tested in a large trial over several years, the low fat diet did not lower cardiovascular events (Women’s Health Initiative) compared to usual diet. On the other hand, low-carbohydrate diets are often not recommended because of the worry that increases in saturated fat would worsen heart disease risk factors. However, data from previous studies suggested that low carb diets were better than low fat for weight loss and some heart risk factors. Our results were consistent with those trials. In addition, our study showed a drop in Framingham risk score which predicts risk of cardiovascular events over 10 years and no other study to date had shown that.

3. What did your study look at?

We compared the effects of a low-carb diet and a low-fat diet on changes in body weight, body composition, and cardiovascular risk factors including blood pressure, lipids, glucose and insulin.

4. What are some of the flaws of a food recall study and did you consider any other form of monitoring?

A 1-day food recall usually cannot reflect people’s usual diet. However, we have conducted 2 days of dietary recall at each of the baseline and clinical visits (months 3, 6 and 12), one day representing a week day and the second day of the dietary recall representing a weekend day. This approach has been used in other counterpart studies. We believe that 2 days of dietary recall should provide similar evidence of adherence to the study dietary goals.

We also had dipstick test to detect the presence of ketones in the urine, as restricting carb down to 40 gram can cause ketonuria.

Additionally, we counted the attendance at the dietary counseling sessions which provided the same behavioral curriculum for weight loss to each group.

5. What were the results of your study?

Participants on the low-carbohydrate diet lost more weight than those on the low-fat diet at 3, 6, and 12 months. At 12 months, those in the low-carbohydrate group lost an average of almost 8 pounds more than those in the low-fat group.
Participants on the low-carbohydrate diet lost more fat mass and did not lose lean mass (muscle) compared to those on the low-fat diet.

Overall, bad cholesterol (low-density lipoprotein cholesterol) that is a predictor of risk for cardiovascular disease decreased on both diets, but good cholesterol (high-density lipoprotein cholesterol) increased more in the low-carbohydrate group.

Physical activity was similar in the groups throughout the study, suggesting that the greater weight loss among participants in the low-carbohydrate group was not because they exercised more.

When we evaluated the black and white participants separately, the results were similar.

6. What should the person looking for fat (weight) loss take away from this study?

A low-carb diet is a good option for those who want to lose weight and reduce cardiovascular risk factors.

7. If you have someone who is 20 lbs, 50 lbs, 100 lbs overweight, where do you suggest they start?

They all can start with low-carb diets if they want to lose weight and reduce heart disease risk.

8. Are there any supplements you suggest for people looking for weight loss?

People may need to know how to plan ahead, read nutrition labels, get healthy fats into their diet (not recommend using butter or partially hydrogenated oils and recommend getting fat from olive oil, canola oil, or other mono and poly unsaturated fat sources), how to measure and control portion sizes, avoid over eating due to stress and more. People also need some exercise. Support from a physician, dietician and/or support group is likely to help readers stay accountable and see results.

9. Who is doing the most interesting research currently in your field? What are they doing?

Christopher Gardner at Stanford, William Yancy at Duke, and Jeff Volek at Connecticut are all conducting research on low-carb diets in various populations.

10. What makes your research different from others?

The diversity of the study group is definitely an important contribution. Previous studies include diabetic patients, or mostly participants with metabolic syndrome or cardiovascular disease or diabetes. Our study only includes healthy obese adults without any clinical disease such as CVD, renal, and diabetes. So the conclusion can certainly apply to the specific population. We are fortunate to recruit large samples of African-Americans and Caucasians and we have examined in either group separately. The conclusion will apply to either whites or African-Americans.

11. What research or projects are you currently working on or should we look from you in the future?

We are still looking at biomarkers of inflammation and other tests by the low-carb and low-fat diets.