That doesn't mean you don't do anything because being active is critical for many aspects of your overall health and wellbeing. I'm just saying you don't have to be a gym junkie to get to your optimal weight.
A lot of evidence shows that aerobic exercises which are great for the heart are minimally effective for weight loss, although they have multiple other benefits including reducing your risk of all forms of chronic illness.
The problem is that, in general terms, exercise does not burn tonnes of calories (unless we're doing heroic amounts of it). It doesn't usually take much additional eating to wipe out any calorie deficit induced through exercise. For example, the energy burned while walking 30 minutes (170 calories) each day will only lose you around one kilogram after 50 days.
In one study of 23 overweight and healthy men engaged in a six month program of exercise, 108 minutes of exercise a week changed the expression of about a third of the genes in their fat cells, including some that relate to the risk of type 2 diabetes and the development of obesity. There were also changes in their waist circumference, waist-to-hip ratio, diastolic blood pressure (the lower of the two blood pressure readings), resting heart rate and levels of HDL-cholesterol. However, their weight only declined by one kilogram on average and they appeared to be no less fat for their efforts.
In a meta analysis of children's weight loss, physical activity interventions were not associated with reductions of BMI. However, there was an association between the interventions and reduction of blood pressure. In a study of overweight people expending either 300 or 600 calories a day exercising for 12 weeks, twice the exercise did not translate into improved weight loss. Those doing 300 calories of exercise lost an average of 2.7kg compared to 3.6kg for the 600 calorie exercise group. Double the exercise led to a 30% extra loss of weight. It's of interest that those exercising for about half an hour a day (300 calories) had a more positive attitude to exercise. Doing larger amounts of exercise is harder which is a barrier to maintaining the exercise.
On the positive side, exercise is great for keeping weight off. The more you are active the less likely you are to put on excess weight. In a study of 25,639 men and women, an increase in weight was associated with higher risk of being inactive 10 years later. Compared with stable weight, a gain in weight of more than 2kg per year is associated with physical inactivity
Exercising for weight loss
But don't stop exercising if you like exercising just yet because the level of exercise also has a large impact on your resting metabolic rate and thermogenesis. There are certain things you can do to improve your weight through exercise. The first is to increase your muscle mass through anaerobic, muscle building exercise. The more muscle you have the higher your resting metabolic rate. That is, the more you burn excess fuel while you are resting.
You can also use exercise and physical activity to increase your thermogensis at critical times, in a sense tricking you body into burning calories before it is stored around your waist.
Insulin is a major contributor to weight gain. The more insulin released with a carbohydrate-dense meal, the more weight you put on around the waist. However, increasing physical activity soon after a meal, even just standing up, increases the cell's requirements for the sugar without releasing extra insulin. Within seconds of any physical activity, one of the non-insulin sugar pathways into the cells, the Glut 4 transporters, are activated to remove sugar from the blood. This reduces blood glucose levels and improves insulin sensitivity (very good for diabetics). That is, less insulin does more work.
Regular exercise also increases the number of Glut 4 transporters. The more you exercise, the more Glut 4 transporters your body will make. Any diabetic will tell you that as soon as they exercise their blood sugar level goes down straight away. This means less to be stored as fat around the waist. In a study of 13 obese patients with type 2 diabetes, post-dinner resistance exercise improved both postprandial glucose and glycation-end products - the damage caused by sugar.
Post-meal physical activity takes the sugar out of the blood before it can cause harm and build up around the waist. Associated with the increase in Glut 4 transporters is that exercise also increases the production of mitochondria which are the energy burning factories of the cells, and a lack of exercise causes numbers to deteriorate.
Exercise for your hunger genes
Like the different foods, exercise can also alter how hungry you feel. In its natural environment your body is in perfect balance and everything feeds back on itself to constantly bring it back into balance. While being more active and exercising generally sends messages to eat more, to keep it all in balance you can also use exercises to suppress your appetite and trick the body.
Exercise can suppress appetite, subsequent energy intake, and alter appetite regulating hormones for a period of time post-exercise. Most people experience appetite suppression following an acute bout of exercise as exercise reduces your immediate feelings of hunger. A study of nine women who had fasted for some time before the experiment found that appetite ratings of the subjects in the exercise group fell for up to two hours after they had been placed on a treadmill for 30 minutes. Similar results have been found with different types of workouts - generally those exercises with greater metabolic and mechanical demand (weight-bearing exercise) showed greater immediate appetite suppression. So, if you are reducing your calorie intake, it is worth being active before a meal as well to reduce those immediate hunger pangs.
There is just no downside to physical activity unless you try to do too much too quickly like the biggest losers.
Standing up for weight loss
Sitting for any length of time may not be good for us, as more and more evidence shows that sedentary behaviours including sitting, watching television, using a computer, and driving a car are risk factors, independent of physical activity, for adverse chronic disease in adults such as obesity, diabetes, heart disease and much more. You can do a long run every night, but if you sit too long during the day you still increase your risk of these chronic conditions. In a study of 2,761 women and 2,103 men without clinically diagnosed diabetes, sitting time was detrimentally associated with waist circumference, BMI (body mass index), weight gain, blood pressure, fasting blood fats, HDL cholesterol, two hour postload plasma glucose, and fasting insulin - a sure way to put on weight. In a meta-analysis using 48 studies, a consistent relationship of sedentary behaviour with mortality was found with weight gain from childhood. That is, the greater the sedentary time in childhood, the greater the weight gain.
It appears that any type of brief, yet frequent, muscular contraction throughout the day, such as standing or moving, may create healthy epigenetic signals, which positively alter the body's biochemistry and metabolism. One of these is a particular muscle chemical, lipoprotein lipase (LPL), a protein enzyme that has been studied in depth because it has a central role in several aspects of fat metabolism. Experimentally reducing movement by sitting had a much greater negative effect on LPL regulation than a positive effect of adding vigorous exercise training on top of the normal level of non exercise activity.
Based on rat studies, the amount of time spent being sedentary influences how our bodies process fats given that leg muscles only produce the lipase lipoprotein (LPL) fat-processing molecule when they are being actively flexed, either by standing or moving. What this shows is that by simply standing up more frequently you increase your muscle activity to reduce sugar and fats in the blood. To achieve even better effects you can stand up after a meal rather than sitting down and watching television.
In support of this one study reported that independent of total sedentary time and moderate-to-vigorous intensity activity time, increased breaks in sedentary time were beneficially associated with waist circumference, body mass index, triglycerides, and 2 hour plasma glucose. In a study of 70 adults involving sitting for nine hours, regular activity breaks lowered plasma insulin levels and lowered plasma glucose when compared with prolonged sitting, even when compared with physical activity. While physical activity lowered plasma triglyceride more with regular activity breaks, activity breaks were more effective than continuous physical activity at decreasing negative blood sugar and insulin levels in healthy, normal-weight adults.
Overall, there is a compelling case for sitting reduction to be included in clinical preventive advice as a key component of "active living", where adults and children are encouraged to "stand up, move more and sit less" across different settings and locations throughout the day. Just standing up every 20 or 30 minutes can have a remarkable health benefit reducing your risk of many chronic illnesses. How simple is that? The results of these studies suggest that, at a minimum, we need to be breaking up our sitting time every 20 to 30 minutes.
DISCLAIMER: Dr Peter Dingle is a researcher, educator and public health advocate. He has a PhD in the field of environmental toxicology and is not a medical doctor.
Dr Peter Dingle (PhD) has spent the past 30 years as a researcher, educator, author and advocate for a common sense approach to health and wellbeing. He has a PhD in the field of environmental toxicology and is not a medical doctor. He is Australia’s leading motivational health speaker and has 14 books in publication.