Tuesday, March 14, 2017

Is Intermittent Fasting A Good Way To Lose Weight?

The Study
Intermittent fasting has been proposed as a method of weight loss in recent years. However, questions remain as to whether it is an effective and safe strategy to manage body weight. A recently published investigation attempts to answer this question. Eighteen men and women completed two three day trials in a crossover design. On the first day, subjects consumed 100% of their energy needs. On the second day, a standardized breakfast was consumed, hormones and appetite were measured and an all you can eat breakfast and lunch was served to all subjects. On day three, an all you can eat breakfast was offered. The second trial started with subjects consuming only 25% of energy needs. Days 2 and 3 in the second trial were identical to the first trial.

There were several important results reported:
1) When subjects restricted their energy intake on day 1, they consumed 7% more energy on day 2. By day 3, they consumed no more calories than they did when they did not fast.

2) Appetite was higher on day 2 when subjects fasted, but not different on day 3.

3) Blood glucose was significantly higher after energy restriction.

4) Energy expenditure was significantly lower on the morning of day 2 after fasting. American Journal of Clinical Nutrition 2016; 104:1545-53.

Take Home Message
This is a fascinating study to me. I have never recommended fasting as a method of weight loss. Is it effective? In the short term, probably. I would argue that it is not in the long term. I think you win the battle but lose the war by fasting. While you will certainly lose some weight, it is my opinion that starving yourself  recruits some of our body’s most effective defense mechanisms. Specifically, metabolic rate is slowed and we start to burn muscle in an effort to spare body fat. This combination makes long term weight loss virtually impossible.

A lot of my concerns about fasting were validated by this study:

1) Subjects were very hungry the day of the fast and even the second day as well. This makes compliance tough because most people are pretty miserable when they are hungry and won’t let themselves stay hungry for long.

2) Subjects consumed more calories the next day than if they had eaten normally.

3) Their energy expenditure was lower the next day. In other words, the fasting seemed to slow down their metabolism. Not good.

4) Most concerning was that their blood sugar and insulin levels were significantly greater when they fasted. This indicates impaired glycemic control, which is not a good thing at all.

5) On a side note, if you are cutting your calories by 75% up to 4 days per week, it is going to be impossible to get enough vitamins, minerals, antioxidants, fiber, etc on those days. These nutrients are hugely important for our health and for chronic disease risk reduction.

In conclusion, there are no shortcuts to losing weight. It takes a lot of work, but the path to a healthy weight and a healthy body is a combination of a balanced diet, a good cardiovascular exercise program and consistent resistance training.

Is Dairy Fat Harmful?

The Study
There has been some question lately as to whether dairy should be consumed in its full fat form or the currently recommended low fat/fat free versions. A very well designed study was recently published that attempts to answer this question using 3 of Harvard University’s most well known cohort studies. 

This was a massive study including 43,652 men from the Health Professional Follow-up Study, 87,907 women from the Nurses Health Study and 90,675 women from the Nurses’ Health Study II cohort. Subjects had their dairy fat consumption measured repeatedly and were followed for over 20 years for incidence of cardiovascular disease (which includes both heart disease and stroke). When dairy fat was compared to a similar amount of carbohydrate (not including fruits and vegetables) there was no difference in risk of cardiovascular disease. However, replacing 5% of energy from dairy fat with:

-polyunsaturated fat resulted in a 24% lower risk of cardiovascular disease.
-vegetable fat resulted in a 10% lower risk of cardiovascular disease.
-whole grains resulted in a 28% lower risk of cardiovascular disease.
American Journal of Clinical Nutrition 2016; 104:1209-17.

Take Home Message
This study is another example of the chasm between well designed nutrition research and popular, internet based fad diet nutrition recommendations. The research literature has consistently shown that high saturated fat consumption is associated with higher risk of heart disease and stroke. Dairy fat is no exception. Low fat/fat free dairy is the way to go. Get your fat from healthy vegetable sources, such as olive oil, canola oil, nuts, seeds, avocados and nut butters.

The Truth About Saturated Fat

The Controversy
When I was studying nutrition in the late 90’s and early 2000’s, it was widely accepted that saturated fat had a negative impact on serum cholesterol and would increase risk of heart disease when consumed in large amounts. In the past few years, there has been some question as to whether or not this is true.

There are several reasons why this doubt has crept into the minds of the public:
1) Several popular diets actively promote the consumption of saturated fats.

2) The idea that coconut oil is a healthy food has really taken off. Proponents of coconut oil argue that different saturated fatty acids will impact health in distinct ways. They argue that coconut oil is high in the type of saturated fats that are health promoting.

3) Several research studies have come out in the past few years suggesting that saturated fat does not increase risk of heart disease.

So is it true, are saturated fats harmless even when consumed in large amounts? Could some types of saturated fats even be good for you?

Saturated Fats
Let’s start from the top. Just what is a saturated fat? 

There are 4 basic types of fats; saturated fat, trans fat, polyunsaturated fats and monounsaturated fats. These different types of fats have very different impacts on our health.

Let’s focus on saturated fats. Saturated fats are fats that contain no double bonds. All of their carbons are saturated by hydrogens. They are found, for the most part, in animal products.

There are several different classes of saturated fatty acids, identified by the number of carbons in their chain length:

Lauric acid: has a 12 carbon chain and is found in coconut oil.
Myristic acid: has a 14 carbon chain and is found in palm and coconut oil.
Palmitic acid: has a 16 carbon chain and is found in palm oil, butter, and beef tallow.
Stearic acid: has an 18 carbon chain and is found in cocoa butter, chocolate and beef.

A study was published recently in The British Medical Journal that sheds a lot of light on this controversial topic.

The Study
The study in question was conducted by Zong et. al. and utilized both of Harvard University’s Nurses’ Health Cohort and Health Professional Follow-up Study (Reference 1). Over 73,000 women and over 42,000 men were followed for 20+ years. Subjects were categorized by saturated fat consumption and monitored for risk of heart disease. What makes this study different is that the researchers didn’t focus exclusively on saturated fat, but also on the individual subtypes of saturated fat most commonly consumed by these subjects. Results were presented for total saturated fat, as well as lauric acid, myristic acid, palmitic acid and stearic acid.

The results were convincing:
-For total saturated fat, there was a statistically significant 18% higher risk of coronary heart disease when comparing subjects consuming the highest amounts of saturated fat to those consuming the lowest amounts.

-When comparing subjects who consumed the most stearic acid to those who consumed the least, there was a statistically significant 18% higher risk of coronary heart disease.

-When comparing subjects who consumed the most palmitic acid to those who consumed the least, there was a statistically significant 18% higher risk of coronary heart disease.

-When comparing subjects who consumed the most myristic acid to those who consumed the least, there was a statistically significant 13% higher risk of coronary heart disease.

-When comparing subjects who consumed the most lauric acid to those who consumed the least, there was a borderline significant 7% higher risk of coronary heart disease.

-Replacing 1% of energy from saturated fat with 1% of energy from:
            Polyunsaturated fat- resulted in an 8% reduction in risk of heart disease.
            Whole grains- resulted in a 6% reduction in risk of heart disease.
            Plant protein- resulted in a 7% reduction in risk of heart disease.

This study tells us several things:
1) Saturated fat, in all of its forms, has the potential to increase risk of heart disease. The increases in risk were statistically significant for total saturated fat, stearic acid, myristic acid and palmitic acid. The only fatty acid that did not reach statistical significance was lauric acid. This relationship was very close to being significant as well (those consuming the most lauric acid had a 7% increased risk of heart disease and the p-value for trend was .05).

2) Replacing saturated fats with healthier foods (polyunsaturated fat, whole grains, plant protein) reduced risk of heart disease in these cohorts.

So, with such strong evidence of harm, why the controversy?
1) Much of the information floating around about saturated fat and coconut oil is not based on research science but on opinion.

2) The few studies that showed no increased risk in heart disease from saturated fat generally used statistical models that replaced saturated fat with carbohydrate. Since most of the carbohydrate that we consume in the U.S. is processed, it is not surprising that replacing one unhealthy food for another does not materially change risk of heart disease. Well designed studies like the one presented here use models that replace saturated fats with more healthful options, such a vegetable based oils, healthy protein and whole grains. These studies show consistent benefit to doing so.

My recommendations to my clients regarding saturated fats are not new. Saturated fat is still associated with an increased in risk of heart disease, regardless of the subtype. It is important to limit consumption to about 7% of calories. When you do substitute the sources of saturated fat in your diet, make sure it is not with refined carbohydrate, but with nuts, avocado, healthy vegetable oils high in poly- and monounsaturated fats, fruits, vegetables, whole grains and vegetable sources of protein.


1) Zong G, Yanping L, Wanders A, et al. Intake of individual saturated fatty acids and risk of coronary heart disease in U.S. men and women. British Medical Journal 2016 355:i5796.

Friday, January 13, 2017

What are some tips to get back on track with my diet after the holidays?

The time between Thanksgiving and New Years day presents some real challenges for those trying to eat healthy and lose weight. The holidays are great and it is a lot of fun celebrating with friends, families and coworkers. Just about everyone puts on a few pounds during this time and that is OK.

However, for many of us, the unhealthy eating continues well into January and even February. This is mostly due to swings in blood sugar that result in increased hunger and cravings for refined carbohydrates, which were likely consumed in large amounts over the last several weeks. The more we eat bread, pasta, white rice and sugar, the more we want these foods.

A couple of extra cheat meals and a few pounds gained during the holiday season are not much of a problem. But if the disordered eating lasts for months, you will put on some serious weight. Even my most successful and dedicated clients will struggle during and after the holidays. Here are a few strategies that help them get back on track:

1) If you have eaten more refined carbohydrates during the holiday season, you will have an increase in cravings for them. You will also be more hungry in general. Step one is to mentally realize this. Tell yourself that you will be hungry for the wrong foods, but will not give into them. Getting your head right and understanding the origin of the cravings is very helpful.

2) Write down your food for 2 weeks. It adds a layer of accountability that gets you back on the right track.

3) Go to the grocery store and load up on all of the right foods. Make it easy to eat healthy. 

4) Plan your meals ahead of time. Think about what you will eat for breakfast, lunch and dinner for the next few days or even a week.

5) Try to limit eating out at restaurants for the first week or two. The warm bread at the table and the menu with a million unhealthy options can be too much when you are craving the wrong foods. 

After a week or two of eating right, you will find that your blood sugar has stabilized and the hunger and cravings for the wrong foods will start to calm down.


Are low fat diets the best option for sustained weight loss?

The Study
Some of the most accomplished professors at Harvard University’s Department of Nutrition conducted a systematic review of weight loss trials to determine if low fat diets increased rate of weight loss compared to other approaches. After comprehensively evaluating the literature, 53 studies were identified that included over 68,000 participants. The findings were very interesting:

-In weight loss trials, low carbohydrate interventions led to significantly greater weight loss than low fat interventions (a difference of about 2.5 lbs.).

-Low fat diets did not lead to a difference in weight change when compared to higher fat weight loss approaches.

-In weight loss trials, higher fat diets led to significantly greater weight loss than low fat diets when groups differed by more than 5% of calories obtained from fat at follow-up (a difference of about 2.5 lbs). The Lancet 2015; 12:968-79.

Take Home Message
Despite decades of advice to the contrary, low fat diets really are not the best strategy for weight loss. There are a few reasons why dieters struggle with a low fat approach:

1) Since protein tends to stay relatively constant in most dieters, when they decrease fat, they increase carbohydrate consumption. In the American diet, this usually means more refined carbohydrates. Since fat acts to stabilize the blood sugar, the low fat, high carbohydrate pattern of eating causes a reactive hypoglycemia in many people that leaves them hungry. Over time, this hunger wins out and the dieter ends up snacking and overeating.

2) These swings in blood sugar also promote higher than normal insulin levels. There is evidence that higher insulin levels promote fat storage through a variety of mechanisms. 

Therefore, for many who attempt a low fat approach to weight loss, they are hungry, eating more, and storing fat at a higher rate. Not a good combination!

While there are certainly people that will do very well on a low fat diet, the research shows that for the typical person trying to lose weight, there are better options.

In both my analysis of the literature and my clinical practice, I have found the Mediterranean approach to be much more effective. This is a moderate fat, moderate carb, low glycemic load diet that stabilizes blood sugar and dramatically decreases hunger. My clients do amazingly well with this approach to weight loss.

Does exercising in the fasted state prevent weight gain?

The Study
Twenty-seven healthy male volunteers were overfed 30% of their body’s calorie needs for 6 weeks. During this overfeeding period, the men were randomized into one of three groups. Group #1 exercised early in the morning, before eating any breakfast. Group #2 ingested carbohydrate before and during their morning exercise. Group #3 was a control group that did not exercise. The two groups that exercised trained with identical programs (360 minutes of cycling and running per week). At the end of the 6 weeks, the control group gained 6.6 lbs. The group that exercised after breakfast gained 3.1 lbs. The group that exercised in the fasting state gained only 1.5 lbs. Journal of Physiology 2010; 588.21: 4289-4302.

Take Home Message
This is a very interesting study suggesting that exercising on an empty stomach may somehow protect us from weight gain. However, there is a major problem with this study that prevents us from drawing this conclusion with confidence. The study does not accurately measure, and does not provide for the reader, the number of calories these subjects consumed each day. The text of the article mentions that the energy intake in all groups was similar. This statement simply means that they were not significantly different statistically. It does not mean they were identical.

The difference in weight gain between the two groups was 1.6 pounds over 6 weeks, which equates to 133 calories per day. It may just be that the fasting group ate a tiny bit less than the breakfast group. The problem is that we don’t know what the difference was in calories per day. Therefore, it is impossible to conclude that exercising on an empty stomach has an impact on weight gain. However, this study has certainly generated an interesting hypothesis that should be tested with an intervention more sensitive to the caloric consumption of the participants. At the very least, this study shows us that exercising for an hour a day helps to prevent weight gain when overeating.

Book Review: Dr. Gundry's Diet Evolution

Next up for review is Dr. Gundry’s Diet Evolution. The author, Dr. Stephen Gundry, is a heart surgeon who has pioneered the development of several surgical devices and techniques. He is a very accomplished physician.

This interesting book presents a weight loss strategy based on an understanding of how our genes work. Dr. Gundry believes that over many thousands of years, our genes have developed defense mechanisms that are now working against us when it comes to our weight and our health. His theory is that by adopting certain dietary and lifestyle habits, we can make these genes work for us instead of against us, resulting in weight loss and improved health. The book is 304 pages long. It is well written and I enjoyed reading it.

5 Things I Really Liked About Diet Evolution
1) It strictly limits sugar and refined carbohydrates like white bread, white rice and pasta. In my opinion, limiting these foods and stabilizing your blood sugar are pivotal to improving your weight and your health.

2) It allows cheat meals. This is a huge part of my recommendations as well. I find regular cheat meals to be essential for several reasons: 1) You don’t have to be perfect to get really good results. 2) The idea of never having a piece of bread, a slice of pizza or a burger again in your life is not at all realistic. 3) Sometimes it is just fun and appropriate to eat junk food. If I am at a Jets or Islanders game, it just does not feel right to be eating a salad or a bowl of black beans.

3) I really like how Dr. Gundry promotes slow and steady weight loss. A huge problem with most weight loss books is that they promise a ridiculous, unsustainable rate of weight loss. A pound a week is what you are looking for. It may not be fast, but it is sustainable and realistic. It is also my opinion that losing weight slowly gives you a much better chance of keeping it off.

4) I like that Dr. Gundry recommends resistance training for weight loss. It is always surprising to me how many weight loss books do not include this essential component.

5) The book contains a large number of well put together recipes.

5 Things I Didn’t Agree With In Diet Evolution
1) This book has a lot of restrictions on what I consider to be very healthy foods. For example, all of the following are considered “Unfriendly” foods and are restricted to some degree: carrots, peas, sweet potatoes, squash, mangos, pineapple, pears, legumes, oatmeal, quinoa, etc. These are all healthy foods I recommend to my clients and I’m not quite sure why they are considered so bad for you on this program.

2) Diet Evolution makes a number of claims that are not supported by the research literature: Here is a small sample:

Eating legumes will slow the rate of weight loss.

Eating whole grains will slow the rate of weight loss.

Milk causes cancer.

Low fat diets have shown to be the most successful for weight loss.

3) The book spends a good amount of time explaining why non-nutritive sweeteners are to be avoided, but includes them in a very large percentage of the recipes.

4) I was really surprised that Dr. Gundry dispels all prospective cohort studies as “silly observations”. I understand that only randomized trials can prove cause and effect. However, they have some very serious limitations when it comes to diet and lifestyle research. For example, ethical issues, short length of follow-up, high drop out rates and low compliance plague most trials concerning our diet and lifestyle. 

In most cases of lifestyle research, longer term cohort studies will give us our best chance of answering our research question. Here is an example; there has never been a single randomized trial to test if cigarette smoking causes lung cancer. Ethical considerations rightfully prevent any such trial from being conducted. However, observational research has consistently shown that smoking causes lung cancer. This is not a silly observation to me! I also found it ironic that later in the book, when discussing the benefits of moderate alcohol consumption, Gundry backs up his claim by citing a reference on alcohol consumption and risk of coronary heart disease in the Health Professional Follow-up study, which happens to be a prospective cohort study.

5) This book is very heavy on vitamin and mineral supplementation. In my opinion, the research has not shown such supplementation to be beneficial and in some cases, it can even cause harm. It never makes sense to me when a dietary program strips a lot of healthy foods out of the diet (such as fruits, legumes, whole grains, etc) and then suggests vitamin and mineral supplementation to fill in the nutritional gaps. Why not just leave the nutrient packed foods in the diet? To me, any diet that we need to supplement with pills to balance our nutrient needs is not a natural diet for humans to consume.

Is Diet Evolution Worth Reading?
Absolutely. This book gets a lot right and the theory of how our genes impact our food choices is a unique take and quite interesting. I would just ease the restrictions on what I consider to be healthy foods such as fruits, vegetables, legumes, whole grains, lean sources of protein and healthy fats.