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Can You Make Exercise Improvements Just By Dieting?

Adam Lotts_PhotoWe’re excited to welcome our Exercise Physiologist, Adam Lotts, as a guest blogger! Adam was born and raised in Richmond, Virginia. He has an undergraduate degree in Kinesiology from The College of William and Mary in Williamsburg, VA and a master’s degree in clinical exercise physiology from East Stroudsburg University in Pennsylvania. He moved to Houston after completing his master’s, where he founded Vexor Medically Advanced Wellness, Inc., specializing in exercise testing for clinical and athletic applications. He also created and managed corporate wellness programming for BP’s offshore operations, and has a passion for educating clients about ways they can push through the struggles of losing weight and leave a sedentary lifestyle behind.


Picture the scenario: you walk into your health care provider’s office. You have not exercised with regularity for well over a decade—maybe two decades. You perform an exercise test to screen for heart disease.

Oh no.

You finished the test with the oxygen consumption levels of a 65 year old…the trouble being that you are 42.  Then a crazy, crazy man called an exercise physiologist tells you that you can have an exercise capacity that is much closer to normal, and you don’t even need to exercise. This man is clearly not only unfit to give professional advice, but he also may need to go through a concussion protocol of some sort.

Hello. I am an exercise physiologist. I am of sound mind (debatable), and I will explain to you why this is completely feasible (albeit incomplete) advice. I’ll start by explaining how exercise capacity is measured, and why it is an important variable regarding cardiovascular health.

In our practice, we evaluate oxygen uptake, or VO2. Everyone has a rate at which they consume oxygen; generally, the more ‘fit’ an individual is, the higher the rate of oxygen consumption per minute. We measure oxygen consumption during exercise in milliliters of oxygen per kilogram of body weight per minute. The way that we acquire all of this oxygen is simple, but according to many patients, is not the most comfortable way to exercise. We capture all of the air exhaled by having a patient breathe into a mouthpiece containing a one-way valve, then we continuously sample it to give us the concentrations of oxygen and carbon dioxide.

The volume of oxygen you consume during exercise, aside from being the gold standard for evaluating where you are on the spectrum of cardiovascular fitness, has enormous diagnostic and predictive values regarding many chronic illnesses, including ischemic heart disease, heart failure, COPD, pulmonary hypertension, mitochondrial dysfunction, and simple shortness of breath (1). Quite simply put, the higher your oxygen uptake, the less likely you are to suffer one of these (among other) chronic illnesses—and if you have already been diagnosed with a chronic illness, improvements in oxygen uptake can commensurately improve symptoms, and in some cases, completely eradicate the disease process.

Alas, the trouble has been—and always will be—that exercise is what is typically prescribed to improve oxygen uptake, and exercise requires that a person…well…exercise to a degree. It is very rare that a patient just outright refuses to exercise; exercise treatment is hindered by scheduling conflicts, energy levels, musculoskeletal or symptom limitations, or psychological barriers like depression, anxiety, or quite simply a lack of motivation or belief that a lifestyle change is achievable. It takes time and certainly a degree of effort to see an exercise regimen bear fruit, and often it is not seen right away on a scale or a waist measurement.


A recent study out of Wake Forest was done to look at the effect of caloric restriction (diet) and/or exercise training over the course of 20 weeks in a group of 100 people who suffered from varying degrees of heart failure. One group dieted, one group exercised, and one group dieted and exercised. The study found that the oxygen uptakes improved as follows:

Exercise group by 1.2 ml/kg/min

Diet group by 1.3 ml/kg/min

Diet + Exercise by 2.5 ml/kg/min

There was a fourth group that literally did nothing, which yielded absolutely no change at all—an absolute shocker.

In other words, the folks who only reduced their caloric intake over the course of the study actually improved their oxygen uptake MORE than the folks who exercised.

How did this happen?

The answer is simple. When the diet group restricted their calories, they lost weight.  If you’ll remember, oxygen uptake is measured in milliliters per kilogram of body weight per minute. If an individual loses weight, even without exercise, they improve the oxygen consumption number because we are now dividing by a smaller body weight number. Let’s look at data from an actual patient of ours:

Patient A – weighing 248 lbs (or 112.72 kg)

Oxygen uptake of 29.2 mL/kg/min

Patient A loses 10% of body weight without exercising, now weighs 223 lbs (or 101 kg)

New oxygen uptake of 32.3 mL/kg/min

Since the patient lost 10% of their body weight, even though they did no exercise at all, they see an improvement in aerobic capacity because the oxygen they consume is now divided among a smaller body. This is a measurable variable pertaining to energy levels as a person begins to lose weight as well.

This wonderful revelation comes with a caveat, however. Although we can see improvement directly correlated with the amount of weight a person loses in absence of exercise, you should still exercise. Aside from casually reminding you the group that did both exercise and diet had an outcome that was almost two times better than the other groups, the metabolic improvements made with regular exercise need to be addressed.  Among many other things, exercise improves stroke volume of your heart, vessel elasticity, reduces symptoms of depression, anxiety, increases mitochondrial function, and improves cellular sensitivity to insulin associated with type 2 diabetes. To put it simply, your body will adapt to whatever you throw at it. If you throw a lot of exercise at it, it begins to prepare itself for the next bout by making the aforementioned changes. If you remain sedentary, these changes don’t happen.

Lastly, it should be said that this study was done on a group of folks who suffered from heart failure. Heart failure essentially is when your heart ‘fails’ to eject a proper amount of blood into circulation. It can be last in a cascade of events starting with hypertension; it can also be brought on by a loss of muscle function after a heart attack, or brought on by kidney insufficiency or failure, among other causes. You can imagine that not having a fully functional heart would be a significant limitation to exercise. Folks that perform an exercise test and enter into a training regimen that do NOT suffer from heart failure will be able to perform a much higher volume of training, and therefore will see much more significant improvements than seen in this study.

It’s the beginning of a new year—and with it comes the dawn of new potential for everyone. Come by PrimeCare and let us show you how you can unlock your potential, and see just how easy it is to improve your aerobic function!


Adam Lotts, MS, Exercise Physiologist




(1) Clinical Recommendations for Cardiopulmonary Exercise Testing Data Assessment in Specific Patient Populations. Circulation. September 5th, 2012



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