I really enjoy my medical conversations with Direct Doctors owners Dr Lauren Hedde and Dr. Mark Turshen.  Dr. Tushen was kind enough to answer a few of my questions recently on exercise and metabolism.  Although I remain an active person, I have definitely noticed a change in my overall exercise profile over the past 20 years.  So, I asked the experts at Direct Doctors why this is so.  Their answers, as always, were exactly what I was looking for.  Here is an excerpt from our conversation:
I was an active athlete into my late twenties. In my thirties and forties, my workouts became more infrequent due to family, a career change, and simply a lack of time.  During this period, I noticed that my workouts didn’t produce the same calorie burning effects and I have since gained weight in my thirties to forties.  What am I doing wrong?  I work out the same duration, eat healthy.  Is it me?
It’s definitely not just you! Unfortunately, as we age, our body composition changes. In general, the more muscle one has as a percentage of their body makeup (and the less body fat), the more calories they will burn with similar activities. As we age, the amount of muscle tends to decrease and and fat accounts for more of our weight, slowing down calorie burning. Exercises you were doing in your 20’s, with more muscle mass, led to increased calorie burning and better maintenance of your weight at that time. These same exercises are great to continue, but for many people will not have the same effect on weight as they age. 
In other words, a 50 year old male doing the same workout as a 20 year old male burns less calories?  What causes this?
Answered above in question 1. However, this is not to say that all is lost. As we age, and especially for those who have gone through a more prolonged period of sedation/being less active, it is obviously still possible to increase lean muscle mass. So although you may not burn calories like you did in your 20’s, you can still burn more calories as a lean and active 40 year old, than an overweight and inactive 40 year old who exercises sporadically. 
Is it a gender related concern or will females go through the same metabolic decreases as they age?
Both men and women go through these same body composition changes as they age. And, similar to aging, gender plays a role in metabolism as well. Men usually have less body fat and more lean muscle than women at the same age and weight and thus burn more calories doing the same exercises than women do. 


Will exercising more frequently increase my metabolism now that I am 40+?
Based on what was noted earlier, working out multiple times a day could increase metabolism and help that increase be maintained for longer periods of time during the course of the day. However, for the large majority of patients, this is just not feasible. The recommendations are to get at least 30 minutes of exercise 5-7 days a week. As a basic rule of thumb, weight loss was, is and always will come down to burning off more calories than you take in. As we get older, we discussed how burning calories gets a little more difficult. So it becomes even more important to watch our diet (i.e. what we take in). Also, there is good evidence that doing shorter, high intensity, interval training is more beneficial on many levels that consistently doing long cardio workouts. This is a good way to increase lean muscle mass (and as we discussed, this does boost metabolism) and weight loss has been shown to be more achievable with this regimen. In a recent 2015 Canadian Cardiology study, they found that patients with type 2 diabetes had larger improvements in both their diabetes and cholesterol levels three months after participating in high-intensity bursts of exercise, compared with those in the conventional sustained-exercise program group.
Direct Doctors
If you experience a slow metabolism, is this a cause to seek a medical professional for the possibility of diseases such as Diabetes, Heart Disease, or other Cardiovascular diseases?
Monitoring of weight, diet, exercise, overall health and these diseases in particular should be a naturally occurring part of your interactions with your primary care doctor. There are definitely specific gender, age, symptom and family history combinations that warrant screening for certain diseases though no one patient is alike. We feel that health and health care really happen continuously and not just when you see your doctor in person. That is why we partner with our patients to monitor their health, and especially their lifestyle choices, track progress and act as supportive health coaches for those that need it. 
Dr. Mark Turshen, MD
Physician/Owner, Direct Doctors, Inc.