Research Update

Do Fruits And Vegetables Help You Live Longer?

The Study

In a Swedish Cohort study, 71,706 men and women aged 45-83 were followed for 13 years to examine the effect of fruit and vegetable consumption on mortality. When compared to subjects consuming 5 servings of fruits and vegetables per day, subjects who never ate fruits and vegetables lived 3 years shorter and had a 53% increased risk of mortality. The authors believed the difference in mortality was due to the fruit and vegetable consumer’s lower rates of cardiovascular disease and cancer. American Journal of Clinical Nutrition 2013; 98:454-9.

Take Home Message

Fruits and vegetables are the healthiest things you can eat, aim for a minimum of 5 servings per day, more is better.

 

Do Nuts Make You Fat?

The Study

Although nuts are an extremely healthy food, many avoid them because they fear their high fat content will cause weight gain. A recently published meta-analysis examined this question. Thirty-three randomized controlled trials were included in this meta-analysis. The results were very interesting. When comparing diets that included nuts to diets that did not, researchers found no increases in body weight, BMI, or waist circumference. In fact, all three were lower in the nut groups, although these differences did not reach statistical significance. The authors believed that the protein and fiber in nuts increase satiety, and that is why they were not associated with weight gain. American Journal of Clinical Nutrition 2013; 97:1346-55.

Take Home Message

Nuts are an awesome food. They are high in healthy fats, protein, fiber, minerals, and phytochemicals. Feel free to include nuts in your diet without fear of them tipping the scale in the wrong direction. Just be reasonable with your portions.

 

 

What Should I Weigh?

When I meet a new weight loss client, one of the first questions I ask is, “How much weight would you ideally like to lose?” Usually they turn around and ask me, “Well, how much do I need to lose?”

My primary goal is to get my clients down to a point where their weight will no longer increase their risk of chronic diseases like heart disease, stroke, type 2 diabetes, and cancer. A simple and powerful measure of how your weight will affect your risk of disease is the Body Mass Index.

Your body mass index is your weight in kilograms divided by your height in meters squared. If your body mass index is 25 or lower, your weight is considered normal. If it falls between 25.1 and 29.9, you are considered overweight. If it is 30 or more, you are considered obese.

Risk of chronic disease begins to increase with BMI’s over 25 and rises sharply with BMI’s over 30. I always have my clients shoot for a BMI under 25. While the BMI measure isn’t perfect, there is a ton of solid research behind the numbers, so I always have my clients start there.  

The Center for Disease Control has a free BMI calculator (click here). You can use this calculator to figure out your BMI today and also what weight you need to reach to get it under 25. There are also a variety of BMI calculator apps for your Smartphone. Just go to your app store and type in “BMI calculator” and you’ll get a number of options to download, many of which are free.

 

 

 

 

 

Research Update: High Glycemic Carbs And Your Brain

Effects of dietary glycemic index on brain regions related to reward and craving in men. American Journal of Clinical Nutrition 2013; 98(3):641-47.

Objective

The goal of this investigation was to examine the effect of glycemic index on brain function during the late post-prandial period (4-5 hours after eating a meal).

Methods

Twelve overweight men consumed two liquid meals on separate occasions. The meals were identical in calories, macronutrients, and palatability. The only difference between the meals was that one had a glycemic index of 84, and the other had a GI of 37. Brain activity was then measured by MRI four hours after consumption of each meal. Blood glucose, insulin, and hunger were also measured repeatedly during the post-prandial period.

Results

Plasma glucose was significantly lower and hunger was significantly greater four hours after the high glycemic meal when compared to the low glycemic meal. The high glycemic preload also elicited a greater brain activity centered in the right nucleus accumbens. This area of the brain is associated with reward and food craving.

Comment

This is a fascinating study! We’ve known for years that high glycemic carbs promote a post-prandial dip in blood sugar that leads to an increase in hunger. I always thought that this was governed solely by the endocrine system. This is the first study to show that high glycemic carbs actually change brain activity, particularly in areas that control reward and craving. While this is just one study, it was very well designed.

Take Home Message

If you work with me or have read my books, you know that a low glycemic approach is the key to losing weight and improving health. This study provides even more reason to strictly limit high glycemic carbs like bread, pasta, white rice and sugar. Instead, focus on lower glycemic carbs like fruits, vegetables, legumes, and whole grains.

 

Should eggs be a part of your regular diet?

The controversy surrounding the egg is a great example of the divide between popular opinion and well-designed research in the field of nutrition. Eggs have been vilified for decades because of their high cholesterol content. Many doctors and nutritionists advocate complete avoidance of egg yolks. I recently read a well written review of the current literature on eggs and health in The American Journal of Clinical Nutrition (1). I definitely learned a few new things.  Therefore, I thought that an update on the research concerning eggs and our health would be a great feature article for the 1^st edition of this newsletter.

Why Have Eggs Been Vilified?

Eggs are considered unhealthy for one basic reason: they are high in cholesterol. A single egg has 213 milligrams. The daily recommended intake for dietary cholesterol is 300 mg. per day. Therefore, by consuming 2 eggs at breakfast, you exceed your daily recommendation for cholesterol. The theory behind the advice to avoid eggs is that consuming too much dietary cholesterol will increase risk of heart disease and stroke.

Research On Eggs And Disease

The article I mentioned earlier is a comprehensive review and meta-analysis of all research to date on the association between eggs and our health (1). In a meta-analysis, researchers combine data from many different studies in order to calculate a statistical summary of all published research. It is kind of like dumping all of the subjects from all of the studies into one population and then analyzing the data.

When this was done for eggs, the researchers found no increased risk of heart disease, stroke, or total cardiovascular disease when comparing those consuming one or more eggs per day to those eating less than one egg per week. This is not new or surprising. Past research has shown that dietary cholesterol is only weakly associated with serum cholesterol. In the Nurses’ Health Study, the Health Professional Follow-up Study, and the Framingham Heart Study, there was no association between egg consumption and risk of heart disease (2,3).

However, the meta-analysis found a 42% increased risk of type 2 diabetes when comparing those consuming one or more eggs per day to those consuming less than one egg per week. This was news to me and I found it a bit disturbing. Therefore, I went out and retrieved all of the major studies on eggs and type 2 diabetes and read them for myself.

I found 5 studies, 3 prospective cohort studies (4-6) and 2 randomized controlled trials (7,8). One of the prospective cohort studies showed a 58% increased risk of type 2 diabetes when comparing subjects consuming 1 or more eggs per day to those consuming less than one egg per week (4). The other 2 cohort studies showed no association (5,6).

The 2 randomized trials were of similar design and were conducted by the same research group (7,8). These trials found that consuming 3 eggs per day for 12 weeks did not raise fasting glucose or insulin resistance.

After reviewing the studies, I came to the conclusion that there is far more evidence that eggs do not increase the risk of type 2 diabetes than that they do. However, the study that showed an association was well designed, so we will keep our eyes on this area of investigation.

What Else Is In Eggs Besides Cholesterol?

An egg yolk is very much like a multivitamin supplement. It contains vitamin D, folate, vitamin E, vitamin A, monounsaturated fat, vitamin B12, vitamin B2, essential amino acids, linoleic acid, calcium, and vitamin B1. Egg yolks are, in fact, one of the most nutrient dense foods that you can eat.

Recommendation

I tell my clients to enjoy up to 6 egg yolks per week. This amount does not have any negative impact on cardiovascular disease and will absolutely pack their breakfast with protein and essential nutrients. There are 2 populations that I would alter this recommendation for:

1) Diabetics: There is evidence of an increased risk of heart disease in diabetics that consumed 1 egg per day (2). Therefore, if you are diabetic, I would limit egg yolks to 3 per week.

2) Older men with a diagnosis of prostate cancer: There is some preliminary evidence of an association between consuming 6 or more eggs per week and an increased risk of progression from more benign prostate cancer to a more deadly form (9). There is no evidence of this association for men consuming up to 3 yolks per week. While this area of research is not yet definitive, I’d play it safe and limit myself to 3 eggs per week if I was diagnosed with prostate cancer.

References

1) Shin, et al. Egg consumption in relation to risk of cardiovascular disease and diabetes: A systematic review and meta-analysis. American Journal of Clinical Nutrition 2013; 98:146-59.

2) Hu, et al. A prospective study of egg consumption and risk of cardiovascular disease in men and women. Journal of the American Medical Association 1999; 281:1387-94.

3) Daubes, et al. Eggs, serum cholesterol and coronary heart disease. American Journal of Clinical Nutrition 1982; 36:617-25.

4) Djousse, et al. Egg consumption and risk of type 2 diabetes in men and women. Diabetes Care 2009; 32:295-300.

5) Djousse, et al. Egg consumption and risk of type 2 diabetes in older adults. American Journal of Clinical Nutrition 2010; 92:422-27.

6) Vang, et al. Meats, processed meats, obesity, weight gain and occurrence of diabetes among adults: Findings from Advent Health Studies. Annals of Nutrition and Metabolism 2008; 52:96-104.

7) Mutungi, et al. Dietary cholesterol from eggs increases plasma HDL cholesterol in overweight men consuming a carbohydrate restricted diet. Journal of Nutrition 2008; 138:272-76.

8) Ratliff, et al. Carbohydrate restriction reduces insulin resistance and plasma leptin without modifying appetite hormones in adult men. Nutrition Research 2009; 29:262-68.

9) Richman, et al. Intake of meat, fish, poultry, and eggs and risk of prostate cancer progression. American Journal of Clinical Nutrition 2010; 91:712-21.

New Newsletter

The science of nutrition is young and evolving. The tools to study the associations between our diet and our health are only a few decades old.  We have learned much, but clearly we have a way to go. High quality research is being published monthly that calls into question many of our older ideas about diet and disease. In order to help keep my clients on top of this research, I have decided to create a free newsletter delivered directly to their email address.

The newsletter will be published every 2 months and will provide valuable information on weight loss, nutrition, exercise, and preventative health.  Content will include: feature articles, research updates, book reviews, product reviews, questions and answers, and much more.

I strongly believe in permission based communications.  If you sign up for the newsletter, be rest assured that I will never share or sell your email address to anyone for any reason. You will also have the ability to opt out anytime you like.

If you are interested in signing up for this free newsletter, just click this link: www.drtomhalton.com/newsletter.html  and enter your name and email address.

Here’s to your good health!
Dr. Thomas L. Halton

Questions and Answers: Resistance Training

No matter what your health and fitness goals may be, resistance training, also known as weight lifting, needs to be a part of your program.  It has always surprised me how many people completely ignore this mode of exercise. I believe that this is mostly due to a variety of myths and misconceptions about strength training.  I thought I’d use this post to answer some of my most commonly asked questions about resistance training. Remember, always meet with your doctor to get clearance before starting any new exercise program.

1) I’m trying to lose weight, so I don’t need resistance training, right?

Wrong! Resistance training is a pivotal component of the weight loss process.  There are two reasons why this is so: 1) Once we hit our 25^th birthday, we start to lose muscle mass at the rate of 1% each year as a natural part of the aging process.  This is a problem because every pound of muscle burns roughly 50 calories per day.  So as you age, you are burning fewer and fewer calories each year.  The result is that it is much easier to gain weight.  Weight lifting stops this loss of muscle and can even add to your muscle mass so you burn more calories each and every day, just by breathing.

2) The second reason why weight training is so important has to do with our body’s natural defense mechanisms to weight loss.  When you lose weight without strength training, your body will let a little fat go, and then starts to freak out.  The human body does not consider low body fat a good situation since we evolved in times of food scarcity and famine.  So, it starts to preserve your body fat and burn muscle instead.  It is estimated that weight loss without strength training results in 50% fat loss and 50% muscle loss.  Over time, this will lower your metabolism and make it all but impossible to keep the weight off.  If you add weight training to your weight loss program, you’ll lose virtually 100% fat and keep your metabolism revved up.

2) Won’t I bulk up and become muscle bound if I lift weights?

 

Not at all.  There are different ways to lift weights.  Lifting heavy weights will result in muscle growth and you will notice that you are getting thicker.  However, using lighter weights with higher repetitions will result in lean and toned looking muscle without a noticeable increase in muscle size.  Most of my female clients want this result so I design their programs accordingly.  Some of my male clients want to get bigger and I can certainly help them do that.  Do realize that getting large bulky muscles is not automatically a result of lifting weights.

3) I’m too old for this sort of exercise, right?

Wrong! You can build muscle until the day you die, no matter how old you are.  I have clients in their 80’s who lift weights and enjoy a much higher level of functionality than their peers as a result.

4) How often should I work out?

The goal is three whole body workouts per week, but you can get away with two.  Do not work out two days in a row.  Try to separate your training sessions by at least a day (IE, Monday, Wednesday, Friday or Tuesday, Thursday, Saturday).  Your muscles need time to recover after a workout.

5) What equipment do I need?

If you want to join a gym and use all the fancy machines, feel free to!  I love working out at nice gyms and did so for years.  As I’ve gotten older and much busier with my business, I strongly prefer working out at home.  It is a real time saver.  Women basically just need a few pairs of dumbbells and an exercise mat to get a great workout.  Men generally need a little bit more weight but can get an inexpensive weight set and a basic bench for a small investment.  If you are interested in learning more about equipment for your home gym, check out this older post here.

 

 

 

 

Research Update: Protein Consumption and Subsequent Energy Intake

Protein leverage affects energy intakes of high protein diets in humans. American Journal of Clinical Nutrition 2013; 97:86-93.

Objective: To examine the association between protein consumption and subsequent energy intake.

Methods: This study was a 12 day randomized crossover trial of 40 men and 39 women.  Subjects visited a university cafeteria for breakfast, lunch, and dinner. The foods offered were similar for each of the three 12 day intervention periods, but varied in protein content (5% of calories, 15% of calories, and 30% of calories).  Fat was kept constant at 35% of calories, so the protein was substituted for carbohydrate.  Subjects could eat as much at a meal as they wanted.

The researchers measured total daily caloric consumption for each subject when they were eating low, moderate, and high amounts of protein.  They also measured subjective ratings of hunger and satiety in each of these three conditions.

Results: The results were striking.  When the subjects were eating 5% of calories as protein, they averaged 2,228 calories per day.  When they were eating 15% of calories as protein, they averaged 2,298 calories per day.  When they were eating 30% of calories as protein, they averaged only 1,722 calories per day!  Fluctuations in hunger and desire to eat were attenuated in the high protein group as well.

Discussion: This is a beautifully designed study.  I love crossover trials, because you are using the same subjects for each of the conditions being tested, which all but eliminates sampling error.  The difference between the moderate and high protein groups was 576 calories per day.  This is a dramatic difference that would have a major impact on body weight. 

The research is really beginning to mount on how dietary protein promotes satiety and decreases subsequent energy intake.  The mechanisms aren’t quite clear, but it may have to do with the high nitrogen content of protein foods.  Nitrogen is difficult for our body to process ,so the theory is that when we eat a lot of protein, our body shuts down hunger in order to prevent nitrogen levels from getting too high.

Take Home Message:  If you are looking to lose weight and decrease your hunger throughout the day, add a bit more protein to each meal.  I have my clients shoot for 20-25% of total calories as protein.  I have found this level to be safe and highly effective for weight loss.