Expert Answer: Can exercise help me lose weight?

Written by Romportl, Mark A., APRN, C.N.P., D.N.P.. Mark works in the Division of Endocrinology in Rochester, helping patients who desire to lose weight. 

Being active can absolutely help you on your weight loss journey.  Exercise uses energy in the form of calories, which can in turn lead to weight loss. How much it helps can be difficult to truly estimate.  This question has many variables to consider.

What activity am I doing?

Let’s compare strength/resistance training and cardio/aerobic training.

Resistance training helps with muscle retention, and you will have rest periods between each exercise.

Various forms of cardio are known for raising heart rate and “burning” calories.  You may not have rest periods during cardio sessions in an attempt to burn as many calories as possible.  Therefore your heartrate will be higher for a longer period of time.  This can correlate to more calories burned.

How accurate are exercise equipment or fitness trackers at estimating calorie burn?

Unfortunately, many machines (treadmills, ellipticals, stair climbers, etc.) at local gyms and rec centers may overestimate the calories burned.  This is a marketing tactic so that their brand of machines can become more popular than others in order to boost sales.

When using heart rate data, the accuracy of estimating how many calories used for activities improves.   A study conducted by Stanford University in 2017 took seven popular fitness trackers and showed that heart rates differed by just 5% when comparing each.  However, the formulas and algorithms the devices used to calculate the estimate of how many calories were burned during these exercise sessions was wrong by 27% on the most accurate device, and 93% on the least accurate device!

What if I have been exercising for a while?

If you have been exercising for many months, congratulations on establishing this as a priority in your life!  Something to keep in mind is that your body becomes better adapted to the exercise you do with time, which burns fewer calories as your efficiency improves.  This means that as you progress, you will have to increase the intensity and/or duration of your activity to achieve the same energy expenditure you did when you first started exercising.  Just be careful you don’t overdo it and risk injury when changing or intensifying your exercise regime.  Consultation with a personal trainer or physical therapist is always a good idea to help with learning proper form, equipment use, and programs to help you progress on your activity journey.

So, can I “earn” calories?

Knowing that wrist or phone-based activity trackers commonly give you falsely too much credit for your activity, you should be careful not to eat these calories back if possible.  Exercise can impact appetite, and some people may notice hunger is diminished after activity, particularly in the immediate post-exercise period, while others may feel their appetite is stimulated more, often later that day.  Having a plan to respond to these cues with nutritious foods will help prevent you from wiping out all the hard work you just put in.

Regular exercise has a multitude of benefits despite its somewhat limited capacity to help you lose weight, including:

-lower risk of heart disease, strokes, and many cancers

-helps prevent and manage blood sugar levels

-boosts mental health, mood, and cognition

-stress relief

-increased energy

-improves sleep

So, exercise certainly should be used to help with weight loss efforts, but just beware of false claims when you hear about an exercise-only program promising to melt pounds away overnight.  Weight loss is most successful when supporting multiple aspects of health- not just your activity level, but also your dietary choices and mental wellbeing too!