Is Cardio enough for Weight Loss?

‘Cardio’ is a popular term that people commonly use to convey that they either ‘walked’ or did ‘a run or jog’ for a specific time as part of their regular physical activity. Moreover, they use a treadmill or elliptical in gyms. This physical activity is often done rigorously in an attempt to lose weight. But what is cardio exactly? Does it help in losing weight or offer any health benefits? Let’s look into this concept.

What is Cardio?

The term ‘cardio’ refers to the ‘heart’. Any physical activity that increases breathing and raises heart rate is called cardio exercise. We also call it ‘Aerobic Exercise’. 

Aerobic again implies ‘oxygen’. The inhaling of oxygen rapidly increases the heart rate during an exercise. This stress on the heart and lungs (‘cardiorespiratory’) is perceived, and the body’s systems strive to maintain homeostasis. This also helps the heart, lungs, and circulatory system (pumping and delivering oxygenated blood to all parts of the body) work efficiently to maintain all health parameters.

Importance of Cardio

Any physical activity has its role in fitness and also health. Cardio or aerobic training is not specifically for weight loss, but it provides a lot of health benefits, both physical and mental. Let’s understand the importance of cardio along with a few pieces of evidence about aerobic/cardio exercise routines.

• Though the foremost benefit is to improve endurance by strengthening the heart, it also helps boost blood circulation and improve metabolic parameters such as glucose uptake and oxidation of fatty acids.
• Cardio also improves lung capacity. The oxygen is pushed in through breathing during vigorous exercise, and it is also transported to all the tissues of the body.
• Cardio makes the heart strong and pumps more blood with every beat. 
• Mitochondria also increases the number of muscle cells. These mitochondria utilize oxygen to oxidize both fat and carbohydrates for the release of energy.
• To mobilize stored fat or free fatty acids to release energy, more oxygen is utilized in the pathways. Hence, aerobic activity!
• Cardio exercise can also boost energy levels during the day by releasing endorphins, which also combat mental issues such as stress, anxiety, and depression. 
• Long-term and low-frequency aerobic exercise has been shown to improve mental health in older adults above 60 years. (Yao et al., 2021)
• Cardio helps with improving sleep patterns.
• Aerobic exercise was found to reduce inflammation and improve the femoral bone mineral density in overweight postmenopausal women who are following a weight loss program. (Silverman et al., 2019)
• In a recent randomized controlled trial, cardio types HIIT (high-intensity interval training) and MICT (moderate-intensity continuous training) were performed by subjects where it was observed that energy expenditure increased with either MICT or a combination of HIIT/MICT, but the later modality seems to be associated with significant weight loss (5 kg and 2 kg respectively in 24 weeks program) (Berge et al., 2021).
• In a retrospective study (Van Der Heijden et al., 2009), though no weight loss was observed, there was a substantial improvement in insulin sensitivity in both lean and obese sedentary subjects when moderate aerobic exercises were performed.
• A systematic and meta-analysis study (Thorogood et al., 2011) concluded that in overweight and obese persons, a moderate-intensity aerobic exercise program was shown to be ineffective for weight loss but improved cardiovascular risks and lipid levels along with a proper weight loss diet.

There are immense benefits of aerobic exercise or cardio in all populations, from adolescents to older age groups. 

Is Cardio Enough for Weight Loss?

As we discussed above, cardio plays an important role in managing a variety of lifestyle conditions, but it solely doesn’t help with losing weight. Most people try to run behind those treadmills or walk endlessly to reduce weight, but what matters for losing weight is a calorie deficit. So, what does calorie deficit mean?

It is a basic understanding that we need energy for all basic activities that we perform with movements and other daily activities. Our body also spends energy internally for all the basic metabolic functions, such as digestion, circulation, and respiration. This energy comes from the food that we consume.

Once the body utilizes the required energy for its functions, some energy is also stored as a reserve in muscles, and the liver, and all the remaining energy is stored as fat.

And that’s how, fat cells or body fat accumulates, which results in weight gain. So, to reduce this body fat (fat oxidation), we need to make the body utilize all this extra energy, and hence, we need to consume less energy (calories). We term it as ‘Calorie Deficit’.

Calorie Deficit

A calorie deficit is not a type of diet, but it means eating fewer calories than the maintenance or total daily energy expenditure (TDEE). Now, eating less doesn’t mean skipping food. It means eating healthier foods from all food groups so that there are enough nutrients available to the body. Let’s understand more clearly about calorie deficit with an example.

Let’s assume a person who wants to reduce weight has calculated the following values using the required anthropometric variables – age, gender, height, and weight (for BMR)

BMR = 1500 Kcals

TDEE = BMR * 1.2 (physical activity level for sedentary persons) = 1800 Kcals

Here, 1500 calories are the minimum caloric requirement for a person to perform all basic functions, both voluntary and involuntary. On the other hand, 1800 calories are the maximum calories a person can consume, which means when a person is involved in any kind of physical activity/exercise, he doesn’t gain body weight. 

Now, since there is already high body fat present, the person needs to make a deficit or reduce the calories from TDEE (around 200-300 Kcals, depending on diet history).

And along with this, he has to involve in a daily exercise routine that can involve both cardio and resistance training (important to preserve muscle mass during the fat loss phase).

Take Away

Follow any diet type (keto, intermittent fasting, low-carb), but the only real method to lose weight or fat is to follow a calorie deficit. And not just relying on endless cardio but following a mix of both cardio and resistance training to have all the benefits that can maintain health, both physically and mentally.

American College of Sports Medicine (ACSM) generally recommends 20-60 minutes of aerobic activity (continuous) at least 3-5 times a week, along with 2-3 times per week of resistance training. This varies depending on each individual and their goal.

Author: Praveena Kuchipudi (INFS Faculty)

References

1. Thorogood, A. et al. (2011) ‘Isolated aerobic exercise and weight loss: A systematic review and meta-analysis of randomized controlled trials’, American Journal of Medicine, 124(8), pp. 747–755. doi: 10.1016/j.amjmed.2011.02.037.
2. Berge, J. et al. (2021) ‘Effect of Aerobic Exercise Intensity on Energy Expenditure and Weight Loss in Severe Obesity—A Randomized Controlled Trial’, Obesity, 29(2), pp. 359–369. doi: 10.1002/OBY.23078.
3. Van Der Heijden, G. J. et al. (2009) ‘Aerobic exercise increases peripheral and hepatic insulin sensitivity in sedentary adolescents’, Journal of Clinical Endocrinology and Metabolism, 94(11), pp. 4292–4299. doi: 10.1210/jc.2009-1379.
4. Silverman, N. E., Nicklas, B. J. and Ryan, A. S. (2009) ‘Addition of aerobic exercise to a weight loss program increases BMD, with an associated reduction in inflammation in overweight postmenopausal women’, Calcified Tissue International, 84(4), pp. 257–265. doi: 10.1007/s00223-009-9232-z.
5. Yao, L. et al. (2021) ‘Effect of Aerobic Exercise on Mental Health in Older Adults: A Meta-Analysis of Randomized Controlled Trials’, Frontiers in Psychiatry, 12, p. 1748. doi: 10.3389/FPSYT.2021.748257/BIBTEX.