Obesity is associated with low levels of spontaneous physical activity and reduced ability to burn fat. Exercise is advisable as an approach toward fat loss, even more so when combined with a healthy diet. It is shown that exercise improves fat oxidation and helps to preserve lean body mass (1).

To lose one kilogram of body fat, you must have a deficit of about 7,700 Kcal. Assuming that one wanted to achieve a quarter of a kg of fat loss per week just from exercise, almost 2,000 additional Kcal of physical activity would have to be expended per week. Assuming 5 days of exercise per week, the necessary energy expenditure should be 400 Kcal per day which is roughly 30 minutes per day of high intensity workout or 60 minutes of brisk walking per day (10,000 steps) (1). 

You may see cardio and weights as two distinct types of exercise, but when you put them together, you have a powerful combination for fat loss success (2). That is what is best for fat loss: both. You should do both types of exercise, together, for the best outcome.

Strength and resistance training builds muscle. Muscle has a higher metabolic rate than fat, meaning you burn more energy when you are at rest if you have a higher muscle mass! Therefore, having more muscle raises your resting metabolic rate (energy expenditure) in comparison to having more fat mass. In a weight loss programme, weight training is important to help maintain muscle. Unfortunately when you try to lose weight and find yourself in a calorie deficit (which is necessary), muscle mass is also lost along with fat mass which is why it is important to do strength training when losing weight. 

Another positive aspect of weight training, specifically when you do high intensity exercises of greater than 75% of your maximum heart rate (this also applies to cardio training) is that you continue to burn energy after you stop exercising for up to 72 hours after your session. This is known as excess post-exercise oxygen consumption. The burn is the amount of energy you use after you stop exercising. This is another way of saying your metabolism increases for several hours or longer after an exercise session (3). You can mix weights and movement in circuit training sessions to provide that extra boost, but movement is the key. Ideally you want to be maintaining a high heart rate for a substantial amount of time. 

Here are some tips to optimise fat loss whilst on an exercise regimen.

  1. Lift weights, and make them heavy  – this will increase your muscle mass and help you burn more energy even at rest! The weights workout should be heavy with low reps and high weight. Aim for 8-12 reps, 4-5 sets. This is known as our hypertrophy (muscle gain rep range). 
  2. Combine resistance training with continuous movement in between. In a circuit style training programme where you continue to workout at a moderate intensity for a certain time period. This keeps your heart rate high and the calories ticking over (4).
  3. Don’t forgot about the aerobic cardio style activities. Brisk jogging, fast cycling, swimming, speed walking – anything that you fancy! Time is of the essence here, you want to maximise the calories burnt so push hard for a certain period of time (4). You must do some consistent aerobic or cardio work to burn fat. Try alternating weights and cardio days for four to six days each week, making sure you rest on the seventh.
  4. Do high intensity cardio for shorter times. This will increase the amount of calories you are burning after the session, and not only during it (5) .

Another way to optimise fat loss is to focus on what your personal goal in training is! The American Council of Exercise advises the following (6) ;

  • If your goal is to improve endurance, do cardio first.
  • If your goal is to burn fat and lose weight, do strength training first.
  • If you want to get stronger, do strength training first.
  • On upper-body strength training days, you can do either first.
  • On lower-body strength training days, lift weights first.
  • If your goal is just general fitness, do either first, but maybe start with the one you enjoy less.

How often should you do cardio and weight training per week?

According to the U.S. Department of Health and Human Services, it is recommended for adults to do at least 150 minutes of moderate intensity cardio or 75 minutes per week of vigorous intensity cardio a week, and strength training at least twice a week. Ideally, do weight training three times per week, as this frequency has been shown to be an effective strategy to build muscle and lose fat. Cardio can be done every day if it’s low-intensity, but the higher the intensity, the less frequently you should perform it.

Here is an example of a weekly schedule if you choose one cardio option:

  • Weight training: 2–4 times per week
  • Low-intensity cardio: 5–7 times per week
  • Moderate intensity cardio: 3–4 times per week
  • High intensity cardio: 1–3 times per week

If you are beginning your weight loss and exercise journey, or are an avid exercise guru needing some structure to achieve your goals, book a session with your fitness specialist to get an individually tailored fitness programme. 

By Jenaed Brodell, RD and Fitness specialist 

References 

  1. Borer, K. T. (2008). How effective is exercise in producing fat loss?. Kinesiology40(2), 127-138.
  2. Villareal DT, Aguirre L, Gurney AB, et al. Aerobic or resistance exercise, or both, in dieting obese older adultsN Engl J Med. 2017;376(20):1943-1955. doi:10.1056/NEJMoa1616338
  3. Thornton MK, Rossi SJ, McMillan JL. Comparison of two different resistance training intensities on excess post-exercise oxygen consumption in African American women who are overweightJ Strength Cond Res. 2011;25(2):489-96. doi:10.1519/JSC.0b013e3181bf0350
  4. Greenlee TA, Greene DR, Ward NJ, et al. Effectiveness of a 16-week high-intensity cardioresistance training program in adultsJ Strength Cond Res. 2017;31(9):2528-2541. doi:10.1519/JSC.0000000000001976
  5. Valstad SA, von Heimburg E, Welde B, van den Tillaar R. Comparison of long and short high-intensity interval exercise bouts on running performance, physiological and perceptual responsesSports Med Int Open. 2018;2(1):E20-E27. doi:10.1055/s-0043-124429
  6. American College of Sports Medicine Position Stand (2001). Appropriate intervention strategies for weight loss and prevention of weight regain for adults. Medicine and Science in Sports and Exercise, 33, 2145–2156. 
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