CrossFit 623 - How Long Does it Take to Lose Weight with Exercise?

As you may have guessed… The length of time that it takes to lose weight with exercise highly depends on two main factors: (i) what you eat (aka your diet) and (ii) the amount of time you spend exercising. Other dynamics of weight loss can be associated with your height and weight, which is commonly measured as Body Mass Index (BMI), and how many pounds you are trying to shed based on your starting BMI. The following information will help you to understand how long it will take someone with your body type to lose your desired weight.

Understanding BMI

Before attempting to lose weight, you should get an idea of your BMI. The following information helps you to understand what your BMI means to you.

What is BMI?

BMI is a individual’s weight (measured in kilograms) that is divided by the square of height (measured in meters). BMI will not measure body fat directly; however, research shows that your BMI is relatively closely connected with more direct measures of body fat obtained from skinfold thickness measurements, bioelectrical impedance, densitometry (underwater weighing), dual energy x-ray absorptiometry (DXA) and other methods. Furthermore, BMI appears to be as strongly correlated with various metabolic and disease outcome as are these more direct measures of body fatness. In general, BMI is a quick and easy way of screening for one being underweight, normal weight, overweight, or obese.

How is BMI used?

A high BMI can be an indicator of high body fatness. BMI can be used as a screening tool but is not diagnostic of the body fatness or health of an individual.

To determine if a high BMI is a health risk, a healthcare provider would need to perform further assessments. These assessments might include skinfold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings.

What are the BMI trends for adults in the United States?

The prevalence of adult BMI greater than or equal to 30 kg/m2 (obese status) has greatly increased since the 1970s. Recently, however, this trend has leveled off, except for older women. Obesity has continued to increase in adult women who are age 60 years and older.

Why is BMI used to measure overweight and obesity?

BMI can be used for population assessment of overweight and obesity. Because calculation requires only height and weight, it is inexpensive and easy to use for clinicians and for the general public. BMI can be used as a screening tool for body fatness but is not diagnostic.

How is BMI Calculated?

CrossFit 623 - BMI Calculator
Click to Calculate BMI

BMI is calculated the same way for both adults and children. The calculation is based on the following formulas:

CrossFit 623 - BMI Calculation Formula

How is BMI Interpreted for Adults?

For adults 20 years old and older, BMI is interpreted using standard weight status categories. These categories are the same for men and women of all body types and ages. The standard weight status categories associated with BMI ranges for adults are shown in the following table.

CrossFit 623 - BMI Calculation Weight Status

For example, here are the weight ranges, the corresponding BMI ranges, and the weight status categories for a person who is 5′ 9″.

CrossFit 623 - BMI Calculation Height 5'9"

How What You Eat Effects Weight Loss

According to researchers, a high-protien diet in combination with exercise results in greater lean mass gain and fat mass loss. In other words, eating meats, like fish, chicken, beef, and pork, plus eggs, veggies, nuts, and seeds while conducting intense exercise training will help you lose weight more quickly.

American Society for Nutrition Study

Background: A dietary protein intake higher than the Recommended Dietary Allowance during an energy deficit helps to preserve lean body mass (LBM), particularly when combined with exercise.

Objective: The purpose of this study was to conduct a proof-of-principle trial to test whether manipulation of dietary protein intake during a marked energy deficit in addition to intense exercise training would affect changes in body composition.

Design: We used a single-blind, randomized, parallel-group prospective trial. During a 4-wk period, we provided hypoenergetic (∼40% reduction compared with requirements) diets providing 33 ± 1 kcal/kg LBM to young men who were randomly assigned (n = 20/group) to consume either a lower-protein (1.2 g • kg−1 • d−1) control diet (CON) or a higher-protein (2.4 g • kg−1 • d−1) diet (PRO). All subjects performed resistance exercise training combined with high-intensity interval training for 6 d/wk. A 4-compartment model assessment of body composition was made pre- and postintervention.

Results: As a result of the intervention, LBM increased (P < 0.05) in the PRO group (1.2 ± 1.0 kg) and to a greater extent (P < 0.05) compared with the CON group (0.1 ± 1.0 kg). The PRO group had a greater loss of fat mass than did the CON group (PRO: −4.8 ± 1.6 kg; CON: −3.5 ± 1.4kg; P < 0.05). All measures of exercise performance improved similarly in the PRO and CON groups as a result of the intervention with no effect of protein supplementation. Changes in serum cortisol during the intervention were associated with changes in body fat (r = 0.39, P = 0.01) and LBM (r = −0.34, P = 0.03).

Conclusions: Our results showed that, during a marked energy deficit, consumption of a diet containing 2.4 g protein • kg−1 • d−1 was more effective than consumption of a diet containing 1.2 g protein • kg−1 • d−1 in promoting increases in LBM and losses of fat mass when combined with a high volume of resistance and anaerobic exercise. Changes in serum cortisol were associated with changes in body fat and LBM, but did not explain much variance in either measure.

How Much Exercise Do You Have to Do to Lose Weight?

The key to weight loss, with appropriate dieting, is physical activity. Physical activity is anything that gets you moving and according to the Centers for Disease Control and Prevention, you need to do two types of physical activity: aerobic exercise and muscle-strengthening. The following information is what the CDC recommends that adults with normal weight do to maintain a healthy lifestyle. It is not a recommendation for shedding excess pounds. So it’s safe to say that if you double the recommended physical activity for a healthy adult, you’ll burn more fat and lose weight more quickly and you’ll find success if you are either “overweight” or “obese” in reference to your BMI.

CrossFit 623 - Important Weight Loss Benefits

In-Shape Adults

Adults who are physically active are healthier and less likely to develop many chronic diseases than adults who are inactive. They also have better fitness, including a healthier body size and composition. These benefits are gained by men and women and people of all races and ethnicities who have been studied.

Adults gain most of these health benefits when they do the equivalent of at least 150 minutes of moderate intensity aerobic physical activity (two hours and 30 minutes) each week. Adults gain additional and more extensive health and fitness benefits with even more physical activity. Muscle-strengthening activities also provide health benefits and are an important part of an adult’s overall physical activity plan.

We know 150 minutes each week sounds like a lot of time, but it’s not. That’s 2 hours and 30 minutes, about the same amount of time you might spend watching a movie. The good news is that you can spread your activity out during the week, so you don’t have to do it all at once. You can even break it up into smaller chunks of time during the day. It’s about what works best for you, as long as you’re doing physical activity at a moderate or vigorous effort for at least 10 minutes at a time.


To sum things up, if you want to lose weight fast you must eat right and exercise at least twice as much as the recommended time; especially if you are a good few pounds overweight or suffer from obesity. In effort to “eat right,” you must consume a high-protein diet, which can be accomplished through eating plenty of meat or taking protein supplements. If you’re looking for a good diet that offers this type of eating, you should take time to consider the Paleo Diet. Exercises that offer the highest weight-loss reward are high-intensity ones and it just so happens that this is the basis of CrossFit training. If you want to take your weight loss journey seriously, we highly recommend that you consider joining a CrossFit gym. Going to a CrossFit gym and participating in Daily WODs just three times per week is enough exercise to not only keep your weight off, but to burn off those excess fat reserves and reach your weight loss goal. CrossFit gyms often invite new participants to partake in a class for free, so give it a whirl… You may just find a new way to stay fit and healthy while having fun amongst like-minded people!



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