Energy Balance & Weight Loss
Health messages around diet, exercise and weight loss have become very confusing in recent years, largely due to the multitude of vested interests. However, given the current rates of obesity in Australia it’s time to take a closer look at the energy balance debate and try to simplify the message around weight loss based on credible scientific research.
Ample research supports the concept that the obesity epidemic is associated with both poor quality diet and unbalanced energy intake and cannot be explained by genetic factors alone1. In contrast, dietary patterns consistent with a traditional Mediterranean diet or largely plant-based diet contribute to long-term weight control.
Exercise alone is not enough to stay healthy.
Exercise has been found to be an effective weight loss strategy, particularly in the short-term. Exercise can also improve a person’s metabolic profile and reduce the risk of many chronic health conditions including heart disease and Type 2 diabetes. However, if you think you can eat whatever you desire, as long as you keep exercising and maintain a healthy weight, then it’s time to revisit the foundations of health and nutrition.
An editorial published in the British Journal of Sports Medicine (2015) stated that even individuals at a healthy weight must pay attention to their diet to maintain health for the long term. They cited studies that found individuals with a normal BMI were not immune to metabolic disorders such as hypertension, dyslipidemia (abnormal levels of lipids or fats in the blood) and insulin resistance. All of these health conditions carry an increased risk of some chronic diseases.
Maintaining good health whilst achieving long-term weight loss requires modifying both energy intake and energy expenditure5. Weight loss programs that do not address both tend to be unsuccessful in the long-term.
To live a healthful lifestyle requires both a healthy diet and exercise.
The benefits of diet and exercise work on different mechanisms in the body. Exercise has many benefits beyond weight control, including strengthening muscles, bone density and improving mental health. However, where weight loss is the primary goal the impact of exercise will be limited if changes aren’t also made to a poor diet. This might explain why exercise programs alone generally have a limited or short-term effect on weight loss.
The influence of food intake on body weight can be explained broadly using the energy balance equation, which represents the difference between energy intake (calories or kilojoules from food) and energy output (calories or kilojoules burned from both physical activity and normal body function).
The energy balance equation
When energy output exceeds energy input, the body draws on energy stored in body tissue (fat, muscle etc.), ultimately leading to weight loss. However, it can take a large amount of high intensity exercise to achieve sufficient energy burn for weight loss to occur, particularly without changes to dietary intake. In addition, an increase in exercise often results in increased hunger and food intake, thus making it even harder to achieve weight loss goals.
Let’s look at little closer at energy balance. Generally speaking a 5km walk will burn around 200-300cal (approx. 840-1260kJ) depending on the walk intensity and bodyweight, as well as other factors such as age. However, if that is followed up with a meal at a restaurant, which can quickly exceed 1000cal (4185kJ), then a large number of excess calories (700-800) have been consumed.
Many people often feel hungrier and want to eat more when they’ve exercised. This is common but not necessarily a bad outcome if you’re eating a well-balanced diet. It’s important to remember that not all calories are equal. For example, a small 20g packet of potato chips is 100cal but is also high in saturated fat, high in sodium, low in fibre and provides little or no nutrients. In contrast, a medium-sized banana (118g) contains around 105cal, is low in fat and sodium and is an excellent source of energy, fibre, potassium and vitamins C and B6.
If weight loss is to be achieved by varying only exercise a reduction in the amount of energy consumed in food is also necessary.
Dietary intake that is high in processed foods including saturated fat, sodium, and sugar is associated with weight gain, poor health and contributes to some of the leading causes of death and chronic disease.
No matter what your health goals are, whether it is weight loss or to reduce your risk of disease, you cannot outrun a bad diet. Dietary changes in combination with exercise addresses both sides of the energy balance equation without having to rely heavily on either a highly restrictive diet, or an onerous exercise regime to achieve an energy deficit large enough to cause weight loss.
Two of the best ways to reduce the amount of energy in your diet are;
Replace discretionary foods with healthy core foods and/or
Reduce portion sizes
Lastly, it doesn’t matter what your weight status is, to support good health and achieve sustainable long-term weight loss it is best to incorporate both healthy dietary changes and exercise into a daily routine.
What do I start?
Changing poor eating habits can be challenging, and it takes time and support. I dedicate my time and energy to helping people choose nutritious food and follow eating habits that support good health and healthy ageing.
To your long life and healthy ageing.
Julie Howell
Consulting Nutritionist
References
Romieu I, Dossus L, Barquerra A et al. Energy balance and obesity: what are the main drivers? Cancer Causes Control 2017; 28:247-258. DOI 10.1007/s10552-017-0869-z.
Blair SN, Hand GA, Hill JO. Energy Balance: a crucial issue for exercise and sports medicine. Br J Sports Med 2015; 49:970-971
Mayer J, Roy P, Mitra KP. Relation between caloric intake, body weight, and physical work: studies in an industrial male population in West Bengal. Am J Clin Nutr 1956; 4:169-75
Hand GA, Shook RP, Paluch AE et al. The energy balance study: the design and baseline results for a longitudinal study of energy balance. Res Q exerc Sport 2013; 84:275-86.
Hand GA, Blair SN. Energy Flux and its Role in Obesity and Metabolic Disease. US Endocrinology 2014; 10(1): 59-63.