Wednesday, March 14, 2018

Which Diet Is Most Effective; Low Fat, Low Carb Or Mediterranean

The Study
In this well-designed trial, 322 overweight subjects were randomly assigned to either a low fat diet, a low carb diet or a Mediterranean diet for 2 years. By the end of follow-up, the low fat group had lost 6.4 lbs, the Mediterranean group had lost 9.7 lbs. and the low carb group lost 10.3 lbs. There were some other interesting results:

-The low carb diet was the toughest to adhere to and had the highest drop-out rate.

-The Mediterranean diet had a more beneficial impact on blood glucose and insulin levels in diabetics than the low fat or low carb groups.

-Several risk factors for heart disease improved more on the low carb and Mediterranean diets than on the low fat diet, including reductions in c-reactive protein, triglycerides and ratio of total to HDL cholesterol. The New England Journal of Medicine 2008; 359:229

Take Home Message
The research is really starting to show that a low fat diet is not the path to greater weight loss or improved health. This trial was extremely well designed and not only was the low fat diet less effective for weight loss, it did not improve risk factors for heart disease and diabetes as much as the other two approaches. 

It is important to note that the subjects on the low carb diet were instructed to eat vegetable sources of fat and protein. This was not your typical low carb diet where the subjects were eating bacon, steaks and full fat dairy all day. In fact, when you choose healthy sources of protein and fat, the low carb diet looks a lot like a Mediterranean diet.

For me, the take home messages of this study are:
#1) Healthy fat is a good thing and does not need to be tightly restricted whether your goal is improved health or weight loss.

#2) Too many rapidly absorbed carbohydrates in your diet can make it harder to lose weight and can have a negative impact on your health. 

Is Alternate Day Fasting The Best Way To Lose Weight?

The Study
The efficacy and safety of alternate day fasting as a method of weight loss has not been proven despite the popularity of this weight loss strategy. A study recently published in JAMA Internal Medicine attempts to answer this question. In this investigation, 100 subjects were randomly assigned to one of three groups:

Alternate day fasting: these subjects consumed 25% of their energy needs on “fast days” and then 125% of their energy needs on alternate “feast days”.

Calorie restriction: these subjects consumed 75% of their energy needs each day.

Control group: these subjects had no intervention.

The trial consisted of a 6-month weight loss phase and then a 6-month weight maintenance phase. Primary outcome measures were weight loss and risk factors for heart disease. The results were fascinating:

1) Drop out rates were higher in the fasting group when compared to the calorie restriction group (38% vs. 29%).

2) There were no significant differences in weight loss between the two groups by the end of follow-up.

3) Mean LDL cholesterol rose significantly in the alternative day fasting group.
JAMA Internal Medicine 2017; 177:930-38.

Take Home Message
The results of this well-designed trial are not encouraging for proponents of alternative day fasting. Compared to a more conventional approach, fasting did not improve weight loss, was more difficult to follow and even had a negative impact on health, as higher LDL cholesterol translates to an increased risk of cardiovascular disease. 

Other studies I’ve reported on in this blog have shown evidence of glucose dysregulation with fasting (see them here). While we will wait for more research to be conducted in this area, it appears that fasting is not the way to go if weight loss and improved health are your goals.

Late Night Eating And Weight Gain

The right diet, a good cardiovascular exercise program and a full body resistance training program form the foundation of any weight loss strategy. However, other lifestyle choices can have a big impact on weight loss success. An example of one such lifestyle choice is to limit eating after 8:00 PM. This has been recommended to dieters for generations, but is there any research to back this up? Do people who eat a lot of food after 8:00 PM really gain more weight? In this post, we’ll take a look at what the research tells us.

I find this topic interesting for a couple of reasons. First of all, when I was in high school and college, I could not gain weight for the life of me. I ate all the time, but I had a really high metabolism and was extremely physically active, so I burned off every calorie I put into my body. This probably sounds like heaven to people who were struggling with their weight, but it wasn’t so great. I was really, really skinny.

One of my fraternity brothers told me that to gain weight, I just had to eat 2 peanut butter and jelly sandwiches right before I went to bed. I told him that those few hundred calories wouldn’t make a difference because I was already eating a ton of calories all day. He said it wasn’t just the extra calories, it was when I was eating them that was so important. I gave it a shot. The summer between freshman and sophomore year in college, I ate 2 peanut butter and jelly sandwiches right before I went to bed. I was also working in construction and lifting weights. I put on 30 lbs. in 4 months!

When I became a licensed nutritionist and started working with weight loss clients, I found that a lot of people who were overweight ate a high percentage of their food at night. Having them stop this habit, in addition to changes in diet and exercise, helped them to lose weight. I also noticed that clients that made good progress with their diet and exercise but did not stop eating late at night did not lose much weight at all. I have been recommending to limit late night eating to my weight loss clients for over 15 years.  So what does the research have to say about this?

The Research
Surprisingly, I did not find much high quality research on the topic of late night eating and weight gain. However, I did find several investigations utilizing weaker study designs that hint at a potential association.

1) In a recent cross-sectional investigation published in the American Journal of Clinical Nutrition, 110 college-aged men and women recorded all of their food intake with a time stamp so that the hour of consumption could be accurately recorded. When compared to normal weight subjects, overweight subjects consumed significantly more of their calories 1 hour closer to melatonin onset, which was around 11 PM (Reference 1).

2) Another cross-sectional investigation published in the journal Appetite showed that protein, fat and carbohydrate consumed after 8:00 PM were associated with a higher BMI in a group of 52 volunteers that filled out 7 day food logs (Reference 2).

3) This investigation is a much older study that only had an abstract. I include it here because it is interesting and I have never seen results like this before. In this study, 9 young men were given the same meal at 9:00 AM, 5:00 PM and 1:00 AM (Reference 3). Energy expenditure was measured by indirect calorimetry for one hour before, and six hours after consumption. Dietary induced thermogenesis (DIT) of the meal was calculated as the 3 hours of energy expenditure above basal metabolic rate.

Morning DIT was significantly higher than afternoon DIT (P=.04) and night DIT (P=.0002). Afternoon DIT was higher than night DIT (P=.06). What this means is that these young men burned a higher percentage of their meal’s calories in the morning than they did in the afternoon or at night.

Conclusions And Recommendations
The research on late night eating and weight gain is largely unimpressive. To come to a firm conclusion, you’d really want to see a number of randomized trials and well-designed cohort studies showing an association with late night eating and weight gain. To my knowledge, these studies have yet to be conducted. 

What we are left with are cross-sectional studies that are a much weaker form of evidence. Having said that, several studies I did find suggest a cross-sectional association between eating late at night and gaining weight. One study was a trial that mentions a potential mechanism, but it is so old I could not find the full text to properly evaluate it.

I would say the evidence, while weak, is suggestive of a relationship between late night eating and weight gain. So what are some potential mechanisms at play here?

1) Eating food late at night simply adds extra calories that you would not consume otherwise. 

2) Food consumed late at night is of poor nutritional quality and more likely to cause weight gain. Most people snack on high glycemic carbs like chips, pretzels and dessert late at night. These calories spike the blood sugar and increase fat storage.

3) Another hypothesis is that our metabolism slows down quite a bit at night, so more of what we consume is stored as fat.

4) The thermic effect of food is lower at night, so more of what we eat is stored as fat.

Despite the weak forms of evidence and uncertain mechanisms, I still think it is a good idea to limit eating after 8:00 PM if weight loss is your goal. I have seen this be a very big part of the equation for many weight loss clients over the years.

1) McHill AW, et al. Later circadian timing of food intake is associated with increased body fat. American Journal of Clinical Nutrition 2017; 106:1213-19.

2) Baron KG, et al. Contribution of evening macronutrient intake to total caloric intake and body mass index. Appetite 2013; 60:246-51.

3) Romon M, et al. Circadian variation of dietary induced thermogenesis. American Journal of Clinical Nutrition 1993; 57:476-480.

Saturday, January 13, 2018

Late Night Eating And Weight Gain

The Study
Late night eating is considered a risk for weight gain. However, there has been little research published in this area. In this investigation, 110 college-aged men and women recorded all of their food intake with a time stamp so the hour of consumption could be accurately recorded. When compared to normal weight subjects, overweight subjects consumed significantly more of their calories 1 hour closer to melatonin onset, which was around 11 PM.  American Journal of Clinical Nutrition 2017; 106:1213-19.

Take Home Message
This is a very interesting study. I have noticed for years that my clients who eat late at night don’t seem to lose much weight. The authors of this study were not quite sure why late night eating was associated with weight gain. One hypothesis is that the thermic effect of food decreases late at night. This would translate into more calories being available for fat storage in comparison to the same meal eaten earlier in the day.

Although this investigation is a cross-sectional study, which is considered a weaker form of evidence, I think there is something here. I always have my clients finish eating by 8:00 PM if they are trying to lose weight.  

Grip Strength And Mortality

The Study
In this interesting study, 403,199 members of the UK Biobank Study had their grip strength measured and were followed for 7 years. After controlling for all known confounders, including body mass index, men with the highest grip strength had a 32% lower risk of mortality compared to men with the lowest grip strength. Women with the highest grip strength had a 25% lower risk of mortality compared to women with the lowest grip strength. The American Journal of Clinical Nutrition 2017;106:773-82.

Take Home Message
Grip strength is a pretty good indicator of total strength. This study shows us that the stronger you are, the healthier you are. A possible mechanism at play here is improved glucose metabolism and insulin sensitivity in subjects who regularly lift weights. There is also evidence that weight lifters have improved blood lipid profiles. Resistance training is an often overlooked aspect of health and fitness.  Try to hit the weights at least twice a week and preferably three times a week.  You don’t have to lift heavy weights or spend a lot of time, a simple 20-30 minute full body workout with lighter weights will get the job done nicely.

Book Review: Eat, Drink And Be Healthy

Next up for review is Eat, Drink And Be Healthy, which is an updated 2nd edition of the original work published in 2001. The author, Dr. Walter Willett, is a Professor of Epidemiology and Nutrition at the Harvard School of Public Health. He was the director of the nutrition department at Harvard when I was in grad school. It was an honor to learn from him and you will not find a more impressive and respected nutrition researcher anywhere in the world.

This book is basically a nutrition research encyclopedia, summarizing the most important literature of the past few decades. Dr. Willett organizes the book into 7 diet and lifestyle recommendations that have a powerful impact on risk of chronic disease. The book is 378 pages long. It is extremely well written and researched and I truly enjoyed reading it.  This is the best nutrition book I have ever read and the original version is the 2nd best nutrition book I have ever read.

5 Things I Really Liked About Eat, Drink, And Be Healthy
1) The best thing about this book is that all of the recommendations are based on scientific evidence. There is not a person in the world that understands nutrition research as well as Dr. Willett. He is considered the father of Nutritional Epidemiology and this book is a bible of nutrition research. So many popular diet books make recommendations based solely on the opinion of the author. It is so very nice to read a nutrition book making recommendations that are based on peer-reviewed evidence.

2) The chapter on dietary fats is amazing. There has been a lot of confusion lately about which fats are healthy and which are not that has been generated by popular diet books and the media. Dr. Willett sets the record straight.

3) If you have worked with me personally or read any of my books, you already know that carbohydrate quality is of extreme importance to me. Dr. Willet does an amazing job with his chapter on carbohydrates.

4) I really liked the section on how to decipher nutrition research. The media does a horrible job when disseminating new nutrition research. Their goal is clearly to generate buzz and sell newspapers and they often completely misinterpret research findings. Dr. Willett explains the process of the scientific method and how it is normal and fine to get contradictory results from nutrition research from time to time. Recommendations should never be altered based on just one study. You always want to look at a new study in the context of research done in other populations and with different study designs. Willett really does a good job explaining this.

5) The chapter on weight loss diets is outstanding. Willett goes through each of the popular diet strategies out there and expertly lists the pro’s and con’s of each. This is probably the coolest part of the book, in my opinion.

Is Eat, Drink And Be Healthy Worth Reading?
Absolutely! As I mentioned above, if you could read just one book on nutrition, this would be it. Dr. Willett has changed the way we conduct nutrition research and millions have benefitted from his work. I think this book should be required reading for all high school students. There are very few books out there that can actually change the course of your life after reading them, this is one of them.

Monday, November 13, 2017

Is It Ever OK To Cheat On My Diet?

This is a question I get quite often from my weight loss clients. Not only is it OK to splurge now and again, I actually insist on it!

There are lots of reasons why it is perfectly fine to go off your diet a few times each week:

1) You don’t need to be perfect on your diet to attain your weight loss and health improvement goals. If you are good 90% of the time, you will do awesome. If you eat 21 meals a week, being good 90% of the time leaves 2 meals a week to have some fun.

2) There are times in your life where eating junk food is just fun and appropriate. When I am at a Jets or Islanders game, I am not eating a can of black beans with nuts and a piece of fruit. It is just not going to happen.

3) It is not realistic to be perfect on your diet, so why set yourself up for failure? A big part of my weight loss program is strictly limiting refined carbohydrates like bread, white rice, pasta and desserts. If I told a client that they could never, ever eat any of these foods again, even the most motivated of them would last a few weeks or at most a few months. However, knowing you can have these foods a few times a week makes it much easier to stay on the program long term, which is necessary if you want to hit your goals. At the end of the day, being able to go off your diet twice a week significantly improves long-term adherence.

4) Having the ability to go off your diet gives you options when you are not in control of your food choices. For example, being invited to a wedding or a dinner party can be a big problem if you are trying to be tight with your diet. You don’t really know what you are going to be served. Using one of your splurge meals at the event will allow you to eat whatever is there and not worry about going off your plan.

5) It may even help you to lose weight to overeat a bit twice a week. While I have seen no hard research data on this at all, I feel that overeating a few times a week may relax your body’s natural defense mechanism to a chronic decrease in calories.

I do have just a couple of rules for my clients when it comes to splurging:

1) These are splurge meals, not splurge days. In other words, these are not 10 hour affairs, just 1 meal.

2) No back to back splurges. Keeping a stable blood sugar is the key to long-term calorie reduction. Splurging two days in a row can really throw off your blood sugar and kick start hunger and cravings. I have my clients have a splurge meal midweek on Wednesday and another on Saturday.

3) I have my clients avoid sugar even on splurge meals. It is just too addictive for most people who are trying to lose weight. However, sugar free desserts are permitted on splurge meals for those who have a sweet tooth.