I Should Cut Out Carbs to Lose Weight... right???

A few weeks ago I received many emails from confused clients after the New York Times published an article reporting the findings of a new study showing that a low-carb diet beat a low-fat diet for weight loss. Unfortunately, since this was the headline across most major news outlets afterwards, many people took the basic headline of this study for fact. News articles came out displaying a slab of fatty meat and saying that what we used to think was bad for us now proves to be healthy. Before I could respond to any clients, I had to dive deeper into the study since “low-carb” and “low-fat” is meaningless unless you know exactly what the researchers considered a “low-carb/fat” diet and what the participants actually filled those calories with.

I personally do not think that most health professionals profess “low-fat” diets to patients/clients since we have so much research on healthy mono-unsaturated fats (olive oil, avocado, nuts) and omega-3 fatty acids (flax, hemp, fish oil, etc. ) and their positive impact on health, especially heart disease risk. In fact, for the majority of my clients, I mandate strongly encourage them to consume ½ oz- 1 oz nuts or seeds per day, use avocado as a condiment and in salads (so consume almost every day) and seafood at least 3x/week. When someone is on a low-fat diet, most of their calories will typically come from more added sugars and refined grains, which is undoubtedly related to weight gain and linked to elevated triglycerides and an increased risk of most of our major diseases (diabetes, heart disease, Alzheimer’s, etc). You definitely need an appropriate balance of fats: carbs: protein for optimal functioning- but this ratio depends on your body type and activity level.

In the study as reported by the New York Times, and a follow-up blog article noted, participants in the low-carb group met with nutritionists regularly and were told to limit carbs to <40 g per day. At the end of the study, the low carb group was consuming, on average, 127 g/day whereas the low-fat group was eating 198 g/day (so doing the real low carb thing did obviously not prove to be sustainable).The low-carb group was encouraged to get their fats from healthy sources like the nuts and seeds as opposed to red meat and high-fat dairy. They were also instructed to try to choose fish and leaner proteins and increase consumption of vegetables and beans. Over the course of the study, the “low-carb” group kept saturated fat calories to ~13%, which is nearly impossible if you are consuming all high-fat dairy and high fat meats like many headlines would like this study to prove. So, basically, the “low-carb” group was eating a pretty healthy diet overall. 

Because the low-carb group was eating mostly healthy sources of fat and encouraged to include beans and veggies, this group did have better health-related outcomes compared to low-fat. This goes along with the knowledge we have that healthy fats are important for improving blood lipid profiles. So, you cannot take from this study that all carbohydrates are bad since even the low-carb group was encouraged to consume less processed foods and eat beans (which contain carbs!). As readers, we don’t know exactly what each participant was consuming… the TYPES of foods are very important as are the calories. Their changes in cholesterol and heart disease risk might have to do more with the fact that they were eating more healthy fats and less refined carbs.

For this study, the participants were not told a specific calorie goal, but both groups did cut their calories from beginning to end, on average, by about 500 calories. By the end of the study (12 months), the low-carb group was averaging close to 50 calories fewer than the low-fat group, which can add up to around a 5 lb. greater weight loss per year. This is extremely important to account for, since the study reported that the low-carb group lost 3.3 kg [7.26 lbs] more than the low-fat group over a year.

After this study of 148 participants was published, a meta-analysis study came out comparing low-fat and low-carb diets finding no difference in weight loss. Most of the studies on low-carb diets show they do produce quicker weight loss, but when followed for longer periods of time, the low-carb dieters tend to regain weight. Thus, I like to base my recommendations on meta-analysis since they account for a much larger sample size and various methodologies. Most large controlled trials show very beneficial results on blood lipids and CVD risk for individuals consuming whole grains, fruits, and beans...as well as weight loss. There is very little evidence to support a primarily meat-based diet for lowering cholesterol and weight long term.


MY RECOMMENDATIONS: 

First, never take a news headline as fact; always read the actual study before you formulate your own opinion! I think the big takeaway of this study is that if you cut your calories and fill them with healthy foods ( beans, fish, healthy fats such as nuts and seeds, and tons of veggies) you will lose weight and lower your risk for heart disease. I would like them to do this study again but matching calories and comparing a “low-carb” (<30% calories from carb) and a moderate carb (40-50% calories from carb) which is filled with carbohydrates from ONLY whole grains, low-fat dairy, fruits, and beans. With previous research and meta-analyses, I would expect that the moderate grain group might have better results with blood lipids and longer term adherence. As I frequently mention, most people I know who cut their carb intake too low have a very hard time maintaining that and tend to be the people that binge on junk food or overeat when they go out. I truly believe if you eat only whole grains, TONS of veggies, fruits, low-fat dairy, lean proteins, and include nuts, seeds, and avocado, within your calorie budget you will be successful at losing weight, improving health, and feeling good! If you want to read another summary of this, I recommend the Harvard Medical School’s article on this topic.



References:

1. http://www.nytimes.com/2014/09/02/health/low-carb-vs-low-fat-diet.html?_r=0

2. Bazzano L, et al "Effects of low-carbohydrate and low-fat diets: a randomized trial" Ann Intern Med 2014; DOI:10.7326/M14-0180.

3. http://www.huffingtonpost.com/2014/09/05/low-carb-diet-study-low-fat_n_5763718.html

4. http://www.eurekalert.org/pub_releases/2014-09/mu-adw082914.php

5. Bradley C. Johnston, Steve Kanters, Kristofer Bandayrel, Ping Wu, Faysal Naji, Reed A. Siemieniuk, Geoff D. C. Ball, Jason W. Busse, Kristian Thorlund, Gordon Guyatt, Jeroen P. Jansen, Edward J. Mills. Comparison of Weight Loss Among Named Diet Programs in Overweight and Obese Adults. JAMA, 2014; 312 (9): 923 DOI: 10.1001/jama.2014.10397

6. http://well.blogs.nytimes.com/2014/09/05/new-answers-about-carbs-and-fat/?_php=true&_type=blogs&smprod=nytcore-iphone&smid=nytcore-iphone-share&_r=0

7. Picture Source: http://www.foodsafetynews.com/cavemaneating-350.jpg