Obesity is an increasingly common, yet preventable condition, that is associated with an increased risk of type 2 diabetes and cardiovascular disease. The research shows that the global epidemic of obesity is caused by the over-consumption of high fat, energy dense diets and a sedentary lifestyle. Genetics also play a role in determining how susceptible people are to weight gain but essentially, obesity is the result of an energy intake that exceeds energy expenditure over a protracted period of time. In a nutshell, obesity is generally caused by eating too much and moving too little.
If you consume high amounts of energy, particularly fat and sugars, but don't burn off the energy through exercise and physical activity, much of the surplus energy will be stored by the body as fat. Lets take a closer look.
The average physically active man needs about 2,500 calories a day to maintain a healthy weight, and the average physically active woman needs about 2,000 calories a day. By consuming foods that are high in fat, refined carbs and sugar, we can easily blast right through this amount of calories. For example, eating a large takeaway hamburger, fries and a milkshake can total 1,500 calories – and that's just one meal! There is also very little nutrition in fast foods and junk foods so they are empty calories.
Obesity doesn't happen overnight. It develops gradually over time, as a result of poor diet and lifestyle choices. Here are some other dietary factors that contribute to obesity:
So there are lots of ways to consume more calories than we need on a daily basis. The other side of the equation is exercise. Many people aren't physically active, so a lot of the calories they consume end up being stored in their body as fat.
Lack of Physical Activity
Lack of physical activity is another important factor related to obesity. Many people have sedentary jobs these days that involves sitting at a desk for most of the day. They may also drive to work or take the bus or train. When they get home, they are tired and tend to watch TV to relax, surf the Internet, consume social media and so on. People often say that they don't have time to be physically active because of long work hours and time spent commuting. Basically, not doing much exercise means they are not burning calories and also, they are not stimulating their metabolism.
In some cases, underlying medical conditions may contribute to weight gain. These include:
However, if conditions such as these are properly diagnosed and treated, they should pose less of a barrier to weight loss.
Fat Loss Diet
First off, I would recommend that a person wanting to lose body fat determines their body composition. This can be achieved using body fat callipers, hydrostatic weighing or even a DEXA scan. The dieting process will be a gradual process and the length of time will depend on the amount of weight a person wants to lose.
We will avoid crash diets, starvation diets and fad diets as these often end up in muscle loss too which subsequently leads to a drop in the Basal Metabolic Rate (BMR) which is not good when you want to lose bodyfat. We will be targeting fat loss in this plan. For example, if a person weighs 195 pounds with 20% body fat with a lean body mass of 156 pounds, we are targeting a reduction of 4 calories per pound of lean body mass.
This equates to 625 calories per day. With 3,000 calories per day nutrition plan, we are looking at 2,375 calories a day on this diet plan. A pound of fat contains 3,500 calories so it will take about 6 days to lose a pound of fat. We want to avoid losing fat at a faster rate so as to avoid losing muscle mass too. Using this approach, a person will lose around 5 pounds of fat per month. I would recommend that these calories are reduced evenly from each meal and that this reduction should come from simple carbs and fat. For example, the calorie reduction should come from cutting back on high fat foods, pastries, biscuits, sugary drinks and refined carbs such as white bread and white pasta.
Physical activity increases energy expenditure and also reduces the risk of heart disease more than that achieved by weight loss alone.
Exercise also has a significant effect on the metabolism. Exercise increases the metabolic rate and this helps to control bodyweight by regulating the amount of calories being burned on a daily basis. However, different types of exercise influence the metabolic rate in different ways. Low intensity aerobic exercise will have the least impact on metabolic rate. High intensity cardio exercise has more effect on the metabolic rate and this involves shorter periods of high intensity exercise.
The best exercises for increasing the metabolic rate are weight training and high intensity interval training. During the training itself, the calorie burn will not be that high but the effect on the metabolic rate lasts longer after the training is finished.
Exercise science has come a long way in the last decade and research shows that traditional cardio does not provide the benefits once thought. Clearly, any exercise is better than none but there are more efficient ways of training to achieve the results we want. Studies have shown that short burst training can help to burn fat and increase fitness levels even after 15 or 20 minutes of exercise. A study published in April 2016, investigated whether sprint interval training (SIT) could improve insulin sensitivity and other measures of cardio-metabolic health to the same extent as traditional moderate-intensity continuous training (MICT). SIT involved 1 minute of intense exercise within a 10-minute time commitment, whereas MICT involved 50 minutes of continuous exercise per session.(1)
In this randomised controlled trial, sedentary men performed three weekly sessions of sprint interval training or moderate intensity training for 12 weeks or served as non-training controls. The sprint interval training involved 3 x 20 second ‘all-out’ cycle sprints interspersed with 2 minutes of cycling at a lower level. The moderate intensity training involved 45 minutes of continuous cycling at 70% maximal heart rate. Both protocols involved a 2-minute warm-up and 3-minute cool-down period. The results showed that twelve weeks of brief intense interval exercise improved indices of cardio-metabolic health to the same extent as traditional endurance training in sedentary men, despite a five-fold lower exercise volume and time commitment.
In summary, obesity is basically the result of an energy intake that exceeds energy expenditure over a protracted period of time. In a nutshell, obesity is generally caused by eating too much and moving too little. The good news is that we can combat increases in bodyfat with a healthy diet and fewer calories in conjunction with an exercise routine that increases the metabolism and burns more calories. In the next articles in this series, we'll take a closer look at 3 of the popular diets out there to see how they stack up.
1. Twelve Weeks of Sprint Interval Training Improves Indices of Cardiometabolic Health Similar to Traditional Endurance Training despite a Five-Fold Lower Exercise Volume and Time Commitment. PLoS One. 2016;11(4):e0154075. doi:10.1371/journal.pone.0154075.
Sports & fitness nutritionist, researcher and author on a mission to improve the human condition. Focusing on evidence-based and outcome-based nutrition, training, mindset & environment