Welcome to the August newsletter. The goal of this newsletter is to provide information and analysis of timely topics from recent articles published in the medical literature. I hope you find this information useful and helpful in your health journey.
The end of August certainly feels different this year than it usually does. The baseball season is at the halfway point, NBA and NHL playoffs are going on, and the Tour de France just started. Excuse me for being a bit disoriented...
How can we age well? We know that chronic disease not only shortens lifespans, but also makes our lives more difficult with prescription medication, medical procedures, and restrictions on what we can do. What is the secret? Perhaps it is the idea of being and athlete for life. Athletes have specific goals and work toward them. They focus their nutrition and training on what they need to perform. How can we adopt this mindset? What do we need to be able to do to function in our lives? What barriers do we have to optimum performance? Then we need to design our exercise and nutrition around these goals. The first article looks at the optimum type of exercise for people who are time crunched and insulin resistant (like most of us are).
Late-night eating, we have all done it. But how much does the timing of our dinner affect us? The second study examines the effects of moving dinner later in the evening, much closer to bedtime. What happens to our bodies when we do this? Spoiler alert, it's not good.
We have all been under a lot of stress over the past several months. I would like to leave you this month with an article that made me smile. Heart disease is the top killer in our country. Chocolate tastes good. What if eating chocolate can reduce your risk of the number one killer? Check out the third article for the specifics as well as recommendations for your next chocolate indulgence.
Information is constantly changing. If you are feeling sick or concerned about symptoms, please call me first. We can discuss your symptoms and decide the best course of action for you, including testing. I have saliva based COVID-19 PCR tests available in my office with 24+ hour turnaround. Serum antibody tests can be performed as well with 24-hour turnaround. I continue to work on getting point of care testing and will hopefully have this in place soon, although this landscape is changing rapidly. Please continue to wash your hands frequently, avoid touching your face, and avoid going out if you are sick.
Athlete for Life
Modifying exercise type, intensity, modality, and nutritional status affects the beneficial effects of exercise
Most of my readers know that I emphasize insulin sensitivity as an important health parameter. High insulin levels are inflammatory and underlie many of the problems leading to chronic disease. This study took an interesting approach and looked at exercise for regular people in the same way athletes do. Athletes modify their exercise program based on their individual goals and the needs of their sport. In the same fashion, we can all individualize our exercise based on our goals and needs.
This study examined the effects of exercise in type 2 diabetics. For these people, the emphasis is control of blood glucose levels and the reduction of insulin resistance. What did they find? When done regularly, both aerobic and resistance training improved insulin sensitivity by 40%. That is an excellent improvement. However, combined aerobic and resistance training improved insulin sensitivity by 70% and almost doubled the reduction in A1c (average glucose level over 3 months). Exercise intensity also affected insulin sensitivity with moderate exercise improving insulin sensitivity by 50% while vigorous exercise improved it by 80%. Additionally, they examined the effects of exercising in a fasted state. The blood glucose response to meals was lower for the rest of the day regardless of exercise type but the most effect was seen with combined exercise aerobic and resistance exercise.
- Exercise elicits high energy demands, stimulating cardiorespiratory function and substrate mobilisation and oxidation. Repeated bouts of exercise lead to whole-body adaptations, which improve athletic performance. Distinct exercise modalities and intensities and nutritional conditions pose specific physiological challenges, subsequently inducing different adaptations to training. Athletes often modify these variables to achieve individualised training goals and maximise performance. Exercise training improves glycaemic control in individuals with type 2 diabetes; however, the precise training regimen that confers the most beneficial metabolic adaptations in this population is unknown. In this review, we discuss how modifying exercise type, intensity and modality and nutritional status affects the beneficial effects of exercise on glycaemic control in individuals with type 2 diabetes. Evidence indicates that greater improvements in glycaemic control can be achieved through combined aerobic and resistance training regimens compared with either training type alone. However, the increased frequency of training and a greater number of exercise bouts during combined programmes could be responsible for apparent advantages over a single training modality. The beneficial effects of aerobic exercise on glycaemic control seem to rise with training intensity, with superior adaptations achieved by high-intensity interval training (HIT). In addition, training with low carbohydrate availability ('training low') improves cardiorespiratory function and skeletal muscle oxidative capacity more than conventional training in healthy untrained individuals. Examinations of various training regimens are warranted to assess the safety, efficacy, feasibility and beneficial effects in the type 2 diabetes population. Just like competitive athletes, individuals with type 2 diabetes should be encouraged to adopt training regimens that improve fitness and metabolism.
Bette Davis famously had a pillow in her apartment that said "Old age ain't no place for sissies". I have certainly heard something similar from many patients. We can't retire from life and we can't get a mulligan on our bodies. This means we need to be athletes for life, whether we like sports or not.
I often highlight articles showing how nutrition and exercise greatly affect how we age and our overall health. Last month we looked at the effects of activity (less sedentary time) on cancer outcomes. This month, we are looking at insulin resistance. Insulin resistance is when cells in your muscles, fat, and liver don't respond well to insulin and can't easily take up glucose from your blood. As a result, your pancreas makes more insulin to help glucose enter your cells. As this cycle continues we eventually can't make enough insulin and diabetes results. Additionally, insulin is a storage hormone and we are unable to burn fat for fuel as long as insulin levels are high. It makes sense that improving insulin resistance is important not just for the prevention of diabetes, but also for any of us who would like to lose some body fat. Which brings us to this study. It was done to look at the effects of different types of exercise on blood glucose and insulin levels in type 2 diabetics. But these same effects will hold true for those of us who are not diabetic as well.
What were their conclusions? First, any exercise is important to help with insulin resistance. Both aerobic and resistance exercise was beneficial, improving insulin sensitivity by 40%. This is great, but the real magic happens when we combine the exercises. HIIT (high-intensity interval training) combines these two types of exercise. In this case, the improvement was over 70%. HIIT training is time-efficient, giving comparable effects to aerobic training but with a 40% lower time commitment (1.5 hrs/week vs. 2.5 hours/week). In addition, HIIT tends to raise the intensity of exercise which gives even better outcomes over moderate exercise sessions as higher exercise intensity may confer greater acute insulin sensitization in populations with elevated fasting glucose.
Another tweak to give you more bang for your time. Low carbohydrate availability ('training low') forces the utilization of lipids as a fuel source and promotes mitochondrial biogenesis and superior adaptations in skeletal muscle oxidative capacity. What this means is that exercising after an overnight fast, with depleted liver glycogen, or exercising twice a day, depleting glycogen stores with the first training bout and initiating the second bout with low skeletal muscle glycogen content. This training modality confers superior increases in fatty acid oxidation as well as improving endurance performance over training with high carbohydrate availability.
What is the most effective way to exercise? I would suggest working up to 15-20 minutes of HIIT training a few times a week first thing in the morning on an empty stomach. This can take some getting used to but there can be definite benefits to this approach. In addition, take a walk or participate in other activities (biking, hiking, yoga, etc) you enjoy. Consider taking a walk after dinner to further sensitize you for the morning exercise session. If you already exercise in the morning, experiment with exercising on an empty stomach.
There are several ways to do HIIT type workouts. One is the Tabata workout which is 20 seconds of effort followed by 10 seconds of rest (there are timer apps available). The effort does need to be hard! Many bodyweight exercises such as mountain climbers, jumping jacks, air squats, push ups, and burpees lend themselves to this program. The important thing is to mix things up. Try different types of exercise and see what you enjoy! Here are a few more tips to get started.
By the way, click here if you would like to read more about Clarence Bass, the man in the picture heading for this article. I have followed his work for the past 20 years. Now 83 yrs old, he has maintained mid-single-digit body fat since he was in his 30's and continues to blog at cbass.com.
|Eating a late dinner predisposes to obesity
The incidence of obesity is increasing in the US with our current prevalence of obesity sitting at 42.4%. From 1999-2000 through 2017-2018, the prevalence of obesity increased from 30.5% to 42.4%, and the prevalence of severe obesity increased from 4.7% to 9.2%. So anything that can decrease our risk would be greatly beneficial for our society. This study sought to examine the timing of food consumption with physiologic indicators that contribute to obesity including glucose, insulin, triglycerides and cortisol. They found that moving dinner 4 hours later resulted in nighttime glucose intolerance, reduced fatty acid oxidation and mobilization which would promote obesity if happening on an ongoing basis.
- Context: Consuming calories later in the day is associated with obesity and metabolic syndrome. We hypothesized that eating a late dinner alters substrate metabolism during sleep in a manner that promotes obesity.
- Objective: The objective of this work is to examine the impact of late dinner on nocturnal metabolism in healthy volunteers.
- Design and setting: This is a randomized crossover trial of late dinner (LD, 22:00) vs routine dinner (RD, 18:00), with a fixed sleep period (23:00-07:00) in a laboratory setting.
- Participants: Participants comprised 20 healthy volunteers (10 male, 10 female), age 26.0 ± 0.6 years, body mass index 23.2 ± 0.7 kg/m2, accustomed to a bedtime between 22:00 and 01:00.
- Interventions: An isocaloric macronutrient diet was administered on both visits. Dinner (35% daily kcal, 50% carbohydrate, 35% fat) with an oral lipid tracer ([2H31] palmitate, 15 mg/kg) was given at 18:00 with RD and 22:00 with LD.
- Main outcome measures: Measurements included nocturnal and next-morning hourly plasma glucose, insulin, triglycerides, free fatty acids (FFAs), cortisol, dietary fatty acid oxidation, and overnight polysomnography.
- Results: LD caused a 4-hour shift in the postprandial period, overlapping with the sleep phase. Independent of this shift, the postprandial period following LD was characterized by higher glucose, a triglyceride peak delay, and lower FFA and dietary fatty acid oxidation. LD did not affect sleep architecture, but increased plasma cortisol. These metabolic changes were most pronounced in habitual earlier sleepers determined by actigraphy monitoring.
- Conclusion: LD induces nocturnal glucose intolerance, and reduces fatty acid oxidation and mobilization, particularly in earlier sleepers. These effects might promote obesity if they recur chronically.
Late-night eating. We have all done it. But how bad is it? This study looked at the effect of a later dinner on multiple parameters. They moved the last food intake back from 6 PM to 10 PM while keeping the calorie content of the meals the same. They found that the later meal resulted in glucose and insulin peaks occurring during sleep and that the glucose peaked 18% higher and stayed higher longer. Higher insulin levels were also observed. Additionally, higher glucose and insulin levels were noted the following morning after breakfast. As a result there was a significantly higher amount of time that this group had higher glucose levels. Over time, this would likely have a large effect on insulin resistance, resulting in decreased fatty acid utilization, and would result in increased body weight and metabolic syndrome. The take-home point is eating later is worse than eating earlier and our goal should be to finish eating at least 3-4 hours before bedtime. Stay out of the refrigerator or pantry late at night!
Chocolate tied to lower heart disease risk
Heart disease is the number one killer in our country. Chocolate tastes good. What if great tasting chocolate actually helped reduce our risk of heart disease?
This meta-analysis looked at the association of chocolate consumption on coronary artery disease. The studies selected were from the United States, Sweden, and Australia. Chocolate consumption of >1 time per week or >3.5 times per month were associated with a significantly reduced risk of coronary artery disease.
- Clinical trials have shown that the consumption of chocolate has favorable effects on blood pressure and endothelial function. The previous meta-analysis showed that many dietary components, including chocolate, appear to be beneficial for cardiovascular dis-ease. However, the potential benefit of increased chocolate consumption, reducing coronary artery dis-ease (CAD) risk is not known. We aimed to explore the association between chocolate consumption and CAD.
- We identified six prospective studies with a median follow-up of 8.78 years. The study population was composed of 336,289 individuals with 21,777 diseases. This was composed of 14,043 cases of CAD, 4,667 myocardial infarctions, 2735 cerebrovascular accidents and 332 cases of heart failure. Study subjects included 266,264 individuals from the United States, 68,809 from Sweden and 1216 from Australia. Compared with the consumption of no or less than one time per week, higher chocolate consumption (>1 time per week or>3.5 times per month) was associated with a decreased risk of CAD (pooled RR 0.92; 95% CI0.86-0.99;P<0.001;I2¼48.6%). Compared with the consumption of no or less than one time per week, after excluding Greenberg et al., higher chocolate consumption (>1 time per week) was associated with a decreased risk of CAD (pooled RR 0.90; 95% CI 0.84-0.97;P<0.001;I2¼46.6%). However, during sensitivity analysis excluding Ho et al., compared with the consumption of no or less than one time per week, higher chocolate consumption (>1 time per week or>3.5 times per month) may be associated with a decreased risk of CAD (pooled RR 0.94; 95% CI 0.85-1.03;P<0.001;I2¼52.2%).
- In the present meta-analysis, we found that chocolate consumption (>1 time per week or>3.5 times per month) is associated with a reduced risk of CAD.
Isn't it nice when something that we enjoy is good for us? This study examined the effects of chocolate consumption on coronary artery disease and found an 8-10% reduction in risk in people who consumed chocolate once a week and it appears eating it more often maintained the benefits. We don't know all the exact mechanisms for the benefits of chocolate but flavanols found in chocolate (and tea) have been shown to reduce myocardial infarct size, reduce platelet aggregation, and improve endothelial function. The study didn't specify the type of chocolate to consume but I generally recommend dark chocolate with the highest percentage of cacao you enjoy. Shoot for 70% cacao or higher if possible. The higher the cacao percentage, the higher the flavanols and the health benefits. It is an acquired taste so you can work up to this percentage. If dark chocolate is too bitter, try dark mild chocolate. This is usually around 38% cacao (vs 10% for regular milk chocolate) so it is a good starting point. White chocolate tends to have the highest percentage of sugar so this isn't generally a good choice.
Here and here are lists of some different dark chocolates you may want to try. I tend to enjoy my dark chocolate with a bit of sea salt.
Thank you for taking the time to read through this newsletter. I hope you have found this information useful as we work together to optimize your health. Feel free to pass this on to anyone you think would benefit from this information.
You can find previous newsletters archived on my website here.
As always, if you have questions about anything in this newsletter or have topics you would like me to address, please feel free to contact me by email, phone, or just stop by!
To Your Good Health,
Mark Niedfeldt, M.D.