Wednesday, November 12, 2014

Questions and Answers

Can I use Splenda/Equal everyday?

When my clients learn that eliminating sugar is an absolute key to losing weight, this question naturally follows. Unfortunately, the answer is no, you cannot use non-nutritive sweeteners like Splenda and Equal on a daily basis.

Contrary to popular opinion, non-nutritive sweeteners, like Splenda and Equal, are very well tested and safe to consume in moderation. However, there are 2 problems with them that prevents me from recommending them for everyday use.

Problem #1: They perpetuate cravings for refined carbohydrates. When you eliminate sugar and strictly limit refined carbs like bread, pasta, and white rice, it is typical to go through a withdrawal for a few weeks where you really miss them. After this period, your desire for these foods drops almost to zero. It really is miraculous how you stop craving the wrong carbs when your blood sugar stabilizes. This is a big reason why my clients lose so much weight, they just aren’t nearly as hungry. However, I have found that daily use of the non-nutritive sweeteners perpetuates cravings for sugars and refined carbs. This is problematic because any diet where you are fighting hunger and cravings is destined to fail long term.

Problem #2: The cephalic response. If I was to put your favorite food in front of you, your nose would smell it, your eyes would see it, and you actually release digestive enzymes before you even put a bite into your mouth. This phenomenon is called the cephalic response.  There is some evidence that this response is recruited when consuming non-nutritive sweeteners. Your body senses the sweet taste and releases insulin anyway. This release of insulin can lead to an unstable blood sugar.

In light of these two issues, I only recommend the use of Splenda and other non-nutritive sweeteners twice per week on cheat meals.


Low fat vs low carb for weight loss

The Study
148 obese men and women were randomized to a low fat (<30% of calories) or a low carbohydrate diet (<40 grams per day) for 12 months. By the end of follow up, participants on the low carb diet lost significantly more weight (8 pounds), lost significantly more fat mass, had significantly lower total:HDL cholesterol ratios, had significantly lower triglycerides, and significantly higher HDL cholesterol. Annals of Internal Medicine 2014; 161:309-18.

Take Home Message
This study showed that a lower carb/moderate fat diet not only enhanced weight loss, but also improved risk factors for coronary heart disease. The design of this study was exceptional, with low drop-out rates and high compliance. The only problem I have is with the title: “Effects of low carbohydrate and low fat diets”. By the end of the study, the participants were not really following a traditional low carb diet.

When I think of a low carb diet, I think Atkins, with very little carbohydrate, tons of steak, bacon, cheese and very little fiber. However, the low carb diet in this study was quite different. By the end of the 12 months, the low carb dieters were not consuming the recommended 11% of calories as carbohydrate, but fully 34% of their calories were carbohydrate. They also had very similar amounts of fiber as the low fat group. Although they did include a bit more saturated fat than the low fat group, the majority of their fat consumption (about 70%) was healthy monounsaturated or polyunsaturated fat. Indeed, what they were consuming by the end of follow-up was much more of a Mediterranean diet than a low carb diet.  Either way, this is still a well-designed study showing that a low fat diet is not the way to go for weight loss or improved health.


Tuesday, November 11, 2014

Does a low glycemic eating pattern enhance weight loss?

The Study
Several weight loss diets were compared in a randomized trial of 122 overweight men and women. One of the diets was a moderate carbohydrate, low glycemic index diet and another was a low fat diet. After six months, the subjects consuming the low glycemic index diet had a significantly greater reduction in BMI than the low fat group (-2.45 BMI units for low GI vs. -1.43 for low fat).  Measures of fasting insulin and insulin resistance were also significantly improved for the low GI group. The researchers believed that the increased weight loss with a low glycemic approach may be due to a beneficial impact on glucose and insulin levels and an increased satiety. American Journal of Clinical Nutrition 2014; 100:27-35

Take Home Message
This study provides further evidence that glycemic index is highly relevant for those looking to manage their weight. It also provides further evidence that low fat diets are not the most effective for weight loss or health promotion. In no way should any of this be a surprise to those that work with me or have read my books!

Monday, November 10, 2014

Is Butter Really Back?

Saturated fat has been in the news quite a bit lately. A recently published study has sparked quite the controversy. The study in question appeared in the journal, Annals of Internal Medicine, in March of this year (1). This study was a systematic review and meta-analysis of the research on saturated fat and risk of coronary heart disease. The primary conclusion was that saturated fat has no relationship with risk of heart disease, and that the recommendation to limit saturated fat consumption is not at all scientifically justified.

As usual, the media went overboard with this headline, proclaiming that nutrition scientists have been wrong all along and don’t know what they are talking about.  My two favorite headlines were the Time Magazine article entitled “Eat Butter” (2), and the New York Times piece entitled “Butter Is Back” (3). So, what is going on here? Is butter really back?

The Study
The Annals of Internal Medicine study identified 49 observational studies and 27 randomized controlled trials that investigated the association between saturated fat consumption and risk of coronary heart disease. The data from these studies were combined and a summary risk was computed. When comparing the top third of saturated fat consumers to the bottom third, there was a non-significant 3% increase in risk for coronary heart disease.

Problems With The Annals Study
A good number of nutrition scientists disagreed with the study’s methods and conclusions. Dr. Walter Willett, the chair of the Nutrition Department at the Harvard School of Public health, was among them. He published a comment in Annals concerning the article just a few months after it was published (4). Here is a quick summary of some of the problems he listed: 1) There were gross errors in data extraction. In other words, the researchers didn’t use the most relevant risk estimates from the studies that they included. 2) The omission of important studies. The researchers did not include a number of important investigations, particularly those showing a benefit of polyunsaturated fat consumption on risk of heart disease.

Harvard also sponsored a special teaching session on saturated fat where Dr. Willett mentioned another really important problem with the Annals study: 3) The saturated fat variable was tested in isolation. In other words, saturated fat was investigated on its own, not in comparison to other nutrients.

This third point bears some explaining. When you just look at saturated fat as a variable on its own, it is like comparing it to the rest of the American diet, which is generally unhealthy. So if you are comparing 2 things that aren’t super healthy, one doesn’t look worse for you than the other. 

What is far more useful, is to compare saturated fat to another nutrient in a substitution model. Our total caloric consumption is pretty stable. If we eat less of something, we tend to eat more of something else to replace it. For example, when we reduced our fat consumption in the 1990’s and 2000’s, we replaced it with refined carbohydrate foods, which wasn’t good for our weight or our health. 

A beautifully designed study was published in the American Journal of Clinical Nutrition in 2009 using saturated fat in substitution models (5). This study was a pooled analysis of 11 American and European cohort studies that included a total of 344,696 subjects. When saturated fat was replaced with carbohydrate, there was no association with risk of heart disease. However, when saturated fat was replaced with polyunsaturated fat, there was a 26% lower risk of coronary death and a 13% lower risk of cardiovascular events. Strangely, this study was left out of the Annals review.

In summary, reducing saturated fat is still a good idea. Eating less butter, cream, cheese, and animal fat is still a good recommendation. Replacing those calories with healthy sources of fat, like nuts, vegetable oils, and avocados, is associated with a reduced risk of heart disease. Replacing those calories with carbs, is not associated with risk of heart disease.

Saturated fat may not be as harmful as originally thought, but it is not quite out of jail. Let’s say it is on probation. I still have my clients shoot for a maximum of 7% of their calories as saturated fat, but to include an abundance of healthy vegetable fats in their diet.

1) Chowdhury R, et al. Association of dietary, circulating, and supplement fatty acids with coronary risk. Annals of Internal Medicine 2014; 160:398-406.

2) Walsh, B. Eat butter. Time Magazine 6/23/14 pp. 28-35.

4) Willett WC, et al. Letter in response to: Association of dietary, circulating, and supplement fatty acids with coronary risk. Annals of Internal Medicine 2014; 161:453.

5) Jakobsen MU, et al. Major types of dietary fat and risk of coronary heart disease: A pooled analysis of 11 cohort studies. American Journal of Clinical Nutrition 2009; 89:1425-32.