Wednesday, March 13, 2019

Exercise and inflammation

The Study
In this investigation, 10 subjects who exercised regularly for up to 5 hours per week added 17.5 miles of running to their weekly fitness routine. The researchers were trying to see the impact of intense exercise on the subject’s ability to absorb dietary iron. By the end of follow-up, the subjects had a significant increase in Interleukin-6 levels, which is a biomarker of inflammation. American Journal of Clinical Nutrition 2018;108:1324-1333.

Take Home Message
Inflammation plays a central role in the progression of many chronic diseases, including heart disease, cancer, type 2 diabetes and Alzheimer’s disease. This study is interesting because it provides further evidence that too much exercise is not great for our body. In this investigation, adding 17.5 miles of running to a moderate fitness routine significantly increased body wide inflammation. Moderate exercise has been shown to decrease inflammation, which is one of the many reasons why it is good for you. However, this study shows us that if you do too much, exercise can actually have the opposite effect.

Don’t go overboard with your cardio. Thirty to forty minutes of moderate intensity cardiovascular exercise each day is about as high as I would go. This is the perfect amount to maintain your weight, improve your energy, improve your mood and strengthen your immune system. This amount will also help decrease your risk of today’s most deadly diseases. When it comes to exercise, more is not necessarily better.

Carbohydrate intake and energy expenditure after weight loss

The Study
Following weight loss, resting energy expenditure drops significantly. This is a big reason why so many dieters quickly regain their lost weight. A recently published randomized trial examined if the ratio of carbohydrate to fat impacts resting energy expenditure post weight loss. After a 12% weight loss, 164 overweight subjects were randomized to one of three diets for a period of 20 weeks:

-High Carbohydrate: 60% carbohydrate, 20% fat, 20% protein.

-Moderate Carbohydrate: 40% carbohydrate, 40% fat, 20% protein.

-Low Carbohydrate: 20% carbohydrate, 60% fat, 20% protein.

The primary outcome was total energy expenditure, which was measured by doubly labeled water. The results were fascinating. Subjects consuming the higher levels of carbohydrates had greater decreases in total energy expenditure. Subjects on the moderate carbohydrate diet burned 91 more calories per day when compared to subjects on the high carbohydrate diet. Subjects on the low carbohydrate diet burned 209 more calories per day when compared to the high carbohydrate diet. British Medical Journal 2018;363:k4583.

Take Home Message
This is a really interesting study. The differences in energy expenditure found in this study are highly relevant. Compared to the high carb diet, the extra calories burned in the moderate and low carb diets could prevent 10-20 lbs. of weight regain in a year. 

The researchers believed that the differences in energy expenditure could be due to a lower glycemic index, a lower glycemic load, thermic effects, brown adipose activity, autonomic tone, nutrient cycling, changes in ghrelin levels and/or changes in leptin sensitivity.  

The low carb subjects were found to have lower levels of ghrelin. Ghrelin has been shown to lower energy expenditure and promote fat deposition. The low carb group also had lower levels of leptin. Previous research has shown that lower levels of leptin after weight loss predict less weight regain.

Although more research is needed in this area, going lower carb may make it a lot easier to keep lost weight off permanently. This study provides further evidence that low-fat high carbohydrate diets do not seem to be the path to permanent weight loss.

Does intermittent fasting improve rate of weight loss?

Intermittent fasting has become a popular weight loss strategy in recent years. Many best-selling diet books advocate intermittent fasting as an efficient and natural way to lose weight that is more effective than conventional methods. A randomized controlled trial was recently published that compared an intermittent fasting protocol to a standard weight loss diet where calories where slightly reduced on a daily basis.

The Article
This randomized trial was conducted in Germany and was recently published in The American Journal of Clinical Nutrition (Reference 1). In this investigation, 150 overweight and obese men and women were randomized to one of two weight loss diet groups. The intermittent calorie restriction group (ICR) had a weekly schedule of 5 days without energy restriction and 2 days with an energy restriction that was 75% of usual calories. The goal of the continuous calorie restriction group (CCR) was to reduce calories by 20% each day.

There was a 12 week intervention phase, a 12 week weight maintenance phase, and an additional 26 week follow period for a total of 50 weeks of follow-up. By the end of the 12 week intervention, there was no significant difference in weight loss between the two groups. By the end of the 50 week follow-up, there was still no significant difference between groups in the amount of weight lost.

There were a few other notable findings:
-Physical activity was measured by means of an accelerometer at the start of the study and in Week 12. Levels of physical activity increased by .2% in the continuous calorie restriction group but decreased by 13.4% in the intermittent calorie restriction group.

-By the end of Week 12, fasting glucose had been reduced more in the continuous calorie restriction group than in the intermittent calorie restriction group (-7.6% vs. -2.9%). This difference was statistically significant.

-Five times as many subjects reported uncomfortable side effects in the fasting group compared to the daily calorie restriction group.

Other Research
Several other research publications I have covered in my blog showed negative outcomes with diets using intermittent fasting. These include: an increased LDL cholesterol, glucose dysregulation, increased inflammation, increased hunger and a decreased energy expenditure. If you want to reference these studies, please refer to my review of the Obesity Code (click here).

Conclusions And Recommendations
Despite its recent popularity, intermittent fasting does not appear to be a better weight loss strategy than moderate daily calorie restriction. In fact, it appears to have some real negatives. There is no reason to starve yourself in order to lose weight. I have found that the combination of a blood sugar stabilizing low glycemic load Mediterranean diet, adequate cardiovascular exercise and resistance training is absolutely the way to go if you want to lose weight, feel great and reduce your risk of today’s most deadly diseases.

1) Schubel R, et al. Effects of intermittent and continuous calorie restriction on body weight and metabolism over 50 weeks: A randomized controlled trial. American Journal of Clinical Nutrition 2018; 108:933-45.