Thursday, September 13, 2018

Can I Eat Nuts If I Am Trying To Lose Weight?

Nuts absolutely fit into a weight loss diet.  Here are some of the great things about them:

-They are low glycemic load and therefore are very easy on the blood sugar.

-They contain a healthy source of protein.

-They contain fiber.

-They contain vitamins.

-They contain minerals.

-They contain very healthy sources of fat.

High nut consumption has been associated with a lower risk of heart disease and type 2 diabetes in Harvard prospective cohort studies (Reference 1 and 2).  Now nuts do contain a lot of calories, so you have to be a little careful with your portions.

However, an analysis in the Nurse Health Study showed that women who ate nuts more frequently actually had a reduced risk of obesity compared to women ate them less often (Reference 3).  Feel free to include nuts regularly in your diet, even if you are trying to lose weight.

1) Hu FB et al. Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study. British Medical Journal 1998; 317:1341-45.

2) Jiang R, et al. Nut and peanut butter consumption and risk of type 2 diabetes. Journal of the American Medical Association 2002; 288:2554-60.

3) Bes-Rastrollo M, et al. Prospective study of nut consumption, long term weight change and obesity risk in women. American Journal of Clinical Nutrition 2009; 89:1913-19.

Is Sugar Addiction Genetic?

The Study
In the last few years, evidence suggests that sugar is addictive, similar to alcohol or tobacco. A recent publication tested the hypothesis that sugar addiction is genetic. In this investigation, 108 healthy weight adolescents were given milkshakes with varying sugar contents while undergoing a functional brain MRI. If both parents were overweight, the subject was considered at high risk of becoming overweight. If neither or just one parent was overweight, the subject was considered to be at low risk.

Fifty-three of the subjects were considered high risk and fifty-five were considered low risk. When compared to the low risk subjects, the high risk adolescents showed a significantly greater striatal, gustatory and somatosensory response to the high sugar milk shake. These areas of the brain have been shown to be associated with reward and addiction. American Journal of Clinical Nutrition 2018; 107:859.

Take Home Message
This study tells us several things:
1) Sugar consumption appears to fire up the regions of the brain associated with reward and addiction. The research that this may be the case has been building for some time.

2) The authors conclude that sugar may be more responsible for habitual overeating than other dietary components, such as dietary fat. I agree with them.

3) There may be a genetic component to sugar addiction.

I have observed the addictive nature of sugar for years. In most people that I have worked with, if they have a little sugar, they want more and more. The best bet is to just swear off sugar entirely. Although this is really hard at first, after a few weeks, you’ll hardly miss it.  For most of us, limiting sugar to just a few servings a week is like telling an alcoholic to just have a few drinks per week. It simply doesn’t work. 

Carbohydrate Quality And Osteoporosis

The Study
Osteoporosis is a disease that reduces bone strength and markedly increases risk of fracture. It can dramatically reduce quality of life and ability to function as we age. In this study, 870 subjects from the Spanish based PREDIMED cohort had their glycemic index and glycemic load measured by food frequency questionnaire annually for 9 years. When compared to subjects with the lowest glycemic index, subjects with the highest glycemic index had an 80% higher risk of osteoporotic fracture. When compared to subjects with the lowest glycemic load, subjects with the highest glycemic load had a 320% higher risk of osteoporotic fracture. American Journal of Clinical Nutrition 2018; 107:1035.

Take Home Message
We can add osteoporosis to the growing list of diseases that may occur when we focus on the wrong carbohydrates. The authors believed that the increased blood sugars associated with high glycemic carbs explained the higher risk of osteoporosis through several potential mechanisms:

-Increased inflammation.
-Increased oxidative stress.
-A decrease in osteoblast activity.
-Inhibition of genes involved in osteoblast differentiation.
-An increased excretion of calcium in the urine.

To reduce the glycemic index and glycemic load of your diet, strictly limit refined carbohydrates such as bread, pasta, white rice and sugar. Focus on fruits, vegetables, legumes and whole grains such as oatmeal, brown rice and quinoa. You also don’t want to go too heavy on the carbs. Shoot for about 45-50% of your daily calories as carbohydrate.

Lifestyle Factors And Life Expectancy

A new study was recently published that is so compelling that it deserves its very own feature article. The study is titled “Impact of healthy lifestyle factors on life expectancies in the US population” and it was published in the journal Circulation. The authors of this investigation are the very best of the Harvard School of Public Health’s Department of Nutrition faculty, which includes Dr. Walter Willett, Dr. Frank Hu and Dr. Meir Stampfer (Reference 1).

Most nutrition research focuses on a very specific aspect of lifestyle and its impact on health. For example, “eating red meat increases incidence of colon cancer” or “eating oatmeal decreases serum cholesterol”. What makes this study so interesting is that several lifestyle behaviors are combined so we can see their cumulative impact on health.

The Article
This investigation used subjects from both The Nurses’ Health Study and The Health Professional Follow-up Study for a total of 123,219 men and women. The researchers created 5 lifestyle factors and scored each subject on how well they followed the behavior. Here is the scoring system:

1) Smoking: If the subject never smoked they received a score of 1. If they were a current smoker or had smoked in the past, they received a score of 0.

2) Physical Activity: If the subject engaged in 30 minutes or more of moderate to vigorous physical activity each day they received a score of 1. If they did less than this, they received a score of 0.

3) Alcohol Consumption: Low risk was considered an alcohol consumption of 5 to 15 grams per day for women (which equals 2.5-7.5 drinks per week) and 5 to 30 grams per day for men (which equals 2.5-14 drinks per week). If the subject’s alcohol consumption was in this range, they received a score of 1, if not they received a score of 0.

4) Body Mass Index: Low risk was considered a BMI between 18.5-24.9. If the subject’s BMI was in this range, they received a score of 1, if not they received a score of 0.

5) Diet: Subjects received a score of 1 for this variable if their diet was in the top 40% of the cohort distribution for the Alternate Healthy Eating Index. This diet score is based on a high consumption of vegetables, fruits, nuts, whole grains, polyunsaturated fats and long chain omega 3 fatty acids and a low intake of red and processed meats, sugar sweetened beverages, trans fat and sodium.

Each subject was given a score for the 5 lifestyle factors. A perfect lifestyle would be a score of “5”, while adhering to none of the lifestyle factors would yield a score of “0”.  Subjects were followed for up to 34 years.

When comparing subjects who followed all 5 factors to subjects following none:

-Risk of all-cause mortality was 74% lower in subjects that followed all 5 factors.

-Risk of death from cancer was 65% lower in subjects that followed all 5 factors.

-Risk of death from cardiovascular disease was 82% lower in subjects that followed all 5 factors.

Starting at age 50, women following all 5 factors could expect to live another 43.1 years, while women following none of the factors could expect to live another 29 years.

Starting at age 50, men following all 5 factors could expect to live another 37.6 years, while men following none of the factors could expect to live another 25.5 years

The researchers ran an additional analysis with a stricter criterion for the lifestyle score.

Body mass index: A score of 1 was given to those with a BMI between 18.5 and 22.9.

Physical Activity: A score of 1 was given to those exercising more than 52 minutes per day.

Diet: A score of 5 was given to those in the top 20% of the distribution for the Alternate Healthy Eating Index.

The scoring for smoking and alcohol consumption were kept the same.

Women who followed this expanded score lived 20.5 years longer than those that followed none of the lifestyle factors. For men, the number was 19.6 years.

Conclusions And Recommendations
These results are truly remarkable. To think that by living a healthy lifestyle you could add up to 20 years to your life is amazing. The coolest part is that this study does not take into account quality of life, which is much higher if you follow these habits. If you are able to hit all 5 of these behaviors consistently, you will notice significant and positive changes in your energy, mood, immune system, confidence, mental focus/performance and how you handle stress. 

The take home message on this is one is simple. Go through each of the 5 lifestyle factors and give yourself a score. If you are at 5, you are all set and keep up the good work. If you are hitting less than 5, do your best to work towards a perfect score. Will it be easy to attain all 5 of these? Probably not. However, the effort you put into a healthy lifestyle is paid back to you many times over. It all begins with making your health a priority.

1) Li Y, et al. Impact of healthy lifestyle factors on life expectancies in the U.S. population Circulation 2018 DOI: 10.1161/CIRCULATIONAHA.117.032047.

Friday, July 13, 2018

Non-nutritive Sweeteners And Satiety

The Study
The GI system is believed to contain sweet taste receptors that have an important impact on satiety and hunger. In this interesting study, 12 healthy young men and women had each of the following preloads injected directly into their stomach on separate occasions: 1) 50 grams of glucose 2) 25 grams of fructose 3) 220 mg acesulfame-K, which is a non-nutritive sweetener. Visual analogue scales were used to rate subjective feelings of hunger and satiety. Compared to glucose and fructose, the non-nutritive sweetener initially caused a significantly stronger decrease in hunger and increase in satiety. However, this was followed by a significantly steeper return of hunger. American Journal of Clinical Nutrition 2018; 107:707.

Take Home Message
When I first started studying nutrition, the prevailing wisdom was that weight loss was all about calories in versus calories out. We now know that there is so much more to the story. A huge number of factors influence when and what we eat. Receptors in the GI system are now thought to play a big part. This is a fascinating study.  It utilizes my favorite study design, the crossover trial. In this type of study, each subject receives all interventions on separate occasions and acts as their own control. This really reduces the odds of residual confounding impacting the results. 

In this study, the artificial sweetener caused a significantly greater return to hunger when compared to the calorie containing sugars.  A diet soda or sugar-free dessert is a nice treat for those giving up sugar. However, it is a good idea to limit consumption of artificial sweeteners to just a few times per week. Daily use of non-nutritive sweeteners can have a dramatic effect on hunger and cravings for refined carbs. A few servings per week are not a problem, but daily consumption can really slow weight loss.

Sugar Consumption And Frailty

The Study
This study included 1,973 subjects from Spain over 60 years of age. Sugar consumption was measured with a computer based food frequency questionnaire. Frailty was defined as the presence of three of the following symptoms; exhaustion, low physical activity, slow gait speed, unintentional weight loss and muscle weakness. After several years of follow-up, subjects consuming the most sugar (greater than 36 grams or 9 teaspoons per day) had over twice the risk of frailty when compared to subjects consuming the least amount of sugar (less 15 grams or 4 teaspoons of sugar). American Journal of Clinical Nutrition 2018; 107:772.

Take Home Message
The research literature has shown that added sugar increases risk of obesity, type 2 diabetes, and heart disease. This study shows that it also may have a very negative impact on healthy aging. What makes this study interesting is that it focuses on quality of life and ability to function, rather than a single disease outcome. Do your very best to strictly limit sugar in your diet. Better yet, completely eliminate it.

Book Review: The Obesity Code

Next up for review is The Obesity Code: Unlocking The Secrets Of Weight Loss. The author, Dr. Jason Fung is a Canadian Nephrologist.

This book theorizes that overeating and a sedentary lifestyle have little to do with the obesity epidemic. Dr. Fung believes that obesity is caused by high levels of insulin. The book includes sections on the origins of the obesity epidemic, why overeating and exercise are not that important, Dr. Fung’s new model of obesity, what is wrong with our diet and the solution, which details when to eat and what to eat. The book is 315 pages long and very well written. I enjoyed reading it.

5 Things I Really Liked About The Obesity Code
1) Dr. Fung uses a lot of research to back up his claims. While he does make a few errors in interpreting the nutrition literature, this is a refreshing change in comparison to most best-selling weight loss books.

2) I agree that insulin levels have a lot to do with weight gain. This is a major reason why I recommend a low glycemic load approach for weight loss with my own clients.

3) I totally agree with the restriction on snacking. Even small amounts of extra calories consumed daily can add up to significant weight gain over time. Three balanced meals a day are all we need.

4) I totally agree that added sugars and refined carbohydrates are major causes of weight gain for most of us. Eliminating them needs to be a big part of any weight loss strategy.

5) I like the section on the importance of sleep in weight loss. The research is really beginning to back this up. Short sleep appears to decrease leptin levels and increase ghrelin levels. Both hormones have a lot to do with your ability to lose weight.

5 Things I Didn’t Agree With in The Obesity Code
1) I do not understand Dr. Fung’s theories on exercise. Here is an example:
Page 50: “Physical activity has virtually no relationship to the prevalence of obesity.”
Many studies show that physical activity is a big part of the strategy for those that are successful losing weight. A white paper on my website summarizes a number of these studies (you can find it here).

Page 51: “Exercise has not decreased since hunter gatherer times.” Does Dr. Fung really believe that a sedentary office worker that drives to work and sits in front of a computer all day gets as much physical activity as a caveman who had to walk everywhere he went and hunt and forage for every calorie he ingested?

Page 54: “Exercise has many benefits, but weight loss is not among them”. Strangely, right after this quotation, Dr. Fung cites a randomized trial showing that subjects who exercised 5 times per week lost an extra 10 pounds over 10 months when compared to those that did not exercise.

Generally, exercise by itself is not enough to hit your weight loss goals, but in combination with dietary change, exercise plays a critical role.

2) Similar to his view on cardio, this book makes absolutely no mention of the importance of resistance training. Lifting weights decreases the loss of lean body mass as we lose weight. This makes it much more likely that weight we lose will stay off. Building muscle with weight training increases metabolism. Each pound you add burns roughly 50 calories per day. Burning more calories per day makes it much easier to lose weight.

3) Dr. Fung believes that saturated fat is harmless. He recommends a regular consumption of butter, coconut oil, full fat dairy and beef tallow. He cites a reference from the Nurses’ Health Study to show that total fat is not associated with risk of heart disease (New England Journal of Medicine, 1997; 337:1491). While this is accurate, the rest of this study shows that the type of fat is very important. Saturated fit increased risk of heart disease in this cohort, while mono- and polyunsaturated fat decreased risk. Ironically, after citing this study, Dr. Fung says that saturated fat is fine and that vegetable oils have a negative impact on health. I am not quite sure how he mixed this up. Either way, saturated fat is to be avoided, it increases risk of heart disease.

4) I didn’t agree with the alcohol recommendations in The Obesity Code. Dr. Fung says up to 2 drinks a day are fine. It is my opinion that 14 drinks a week will seriously impede weight loss in both men and women. I have my clients cut down quite a bit on the alcohol if they are trying to lose weight.

5) This book recommends fasting 24 to 36 hours, two to three times per week. I don’t think this is a good idea. In the last year or so, I have blogged on 3 separate studies that examined fasting and were published in top journals. The results were not favorable. Among the findings:

-Drop out rates were higher in those fasting compared to more modest calorie restriction. This means it is much harder to stick to a fasting weight loss plan.

-There was no difference in weight loss between those fasting and those moderately restricting calories.

-LDL cholesterol significantly increased in subjects fasting.

-Several studies showed glucose dysregulation when fasting.

-Subjects fasting had an increase in inflammation.

-Subjects ate significantly more calories than normal the day after fasting.

-Energy expenditure decreased when fasting. 

(You can find these studies, here, here and here.) 

In The Obesity Code, Dr. Fung gives a number of tips when fasting.  Here are a few:

-Take cinnamon and eat chia seeds to reduce hunger.

-Drink salt water when you get dizzy.

-Take a magnesium supplement when you get muscle cramping.

-Drink salt water when you get headaches.

-Take Metamucil when you get constipated.

-Take a multivitamin because you won’t be getting any micronutrients on fasting days.

Maybe it’s just me, but having to do all of these things leads me to believe that fasting is neither a healthy or normal way for the human body to lose weight.

Is The Obesity Code Worth Reading?
Absolutely! It is important for me to read nutrition books that differ from my own personal philosophy. This book makes a lot of really good points. Levels of insulin have much to do with obesity. Limiting sugar and refined carbs are a huge part of the solution. Adequate sleep and limiting snacking are also big players. I would just add a bit to this good advice, notably; lift weights at least twice a week to build muscle, daily cardiovascular exercise is a huge part of weight loss, there is no need to fast, and lastly be sure to limit saturated fats and substitute them with more healthy vegetable fats.