Exercise is not THE answer to weight loss, whether it's "Fat Burning" Cardio or the furnace stoking High Intensity Interval Training (HIIT). Often, when I ask gym goers about their plan to achieve their weight loss goals, the first answer I hear is:
"Exercise! Mainly cardio".
My response, every time, is:
"Great! Cardio is amazing for health & helpful for weight loss".
Then we'll discuss realistic expectations of its impact on weight loss, which will be the topic of today's article.
Straight to Hard Mode
Exercise is incredible for health, in MANY ways. It does help with weight management - but focusing on it as the main driver of weight loss is like going straight to "Hard Mode". This is where we endure the challenges of increased physical activity without seeing a fair return on investment on the scale.
In an extreme scenario, a Dad of two kids, working 40+ hours a week decides it's time to lose some excess weight. In a sudden burst of motivation, he promises himself he'll go to the gym five days per week for an hour. Additional to those minutes in the gym, are required many additional lifestyle tweaks. Morning & evening routines. Packing gym bags & showering before work. Negotiating schedule changes with the family.
Is it worth the priority shift? Absolutely - if it's sustainable.
But this is a classic case of going straight to Hard Mode. And you wouldn't believe how many people do it. For weight loss, Jeff here (let's call him Jeff) could be losing 1/2 kilo per week by doing the exact same thing he usually does, with a few very EASY tweaks, and without overhauling his life. More on this shortly.
We just don't burn that much
Exercise doesn't burn as many calories as we think. Where a fitness tracker may tell you how much energy you expended in a workout, it could be off by quite a bit. And if it were accurate, when we subtract what we would have burned in that 60mins sitting on the couch, the actual exercise energy spent is not much to write home about.
The approximate amount of exercise needed to burn enough calories for 1/2 a kilo weight loss per week would be about 90 mins of brisk walking or 45 mins of jogging. Every Day! This will obviously vary from person to person.
Whereas achieving a calorie deficit of about 500 calories per day, to induce this 1/2kg weight loss, could be done through a few simple and sustainable dietary tweaks:
Remove/replace sugar sweetened drinks
Opt for low fat-dairy & lean meats
Drink booze just when you really want it
Eat more fibre to feel fuller
Have a protein shake/bar instead of a "coconut bliss ball"
Your body is stingy
Although it's intuitive to believe that simply increasing physical activity linearly will lead to higher calorie burn and, consequently more weight loss, research suggests that our bodies are much more complex than this "additive model" implies. There are diminishing returns as the amount of activity increases.
At high levels of energy output, the well-established Constrained Energy Expenditure Model dictates that compensations are made to economise fuel use. Both within the activity and at rest. To keep daily energy output within a narrow range, or "set-point", our body down-regulates non-exercise processes. This could be by unconsciously making us slightly more sloth-like, or by making metabolic processes more energy efficient. The same has been seen when people lose more than 10% of their body weight.
Exercise still matters. A lot
Am I here telling you that you should not waste your time or energy on exercise? Absolutely not!
Exercise contributes to the energy balance equation, and can therefore be very helpful to prevent weight gain, and regain after initial weight loss. For some people, but not everyone, it can help regulate appetite and food cravings. Resistance Training will also prevent muscle loss when in a caloric deficit, shifting body composition toward more muscle and less fat.
Jeff, in our example above, could therefore make those small tweaks to his day and aim to get into the gym for two to three 45-minute sessions. Weight training twice per week and one cardio session would realise an impressive shift in his body shape over a few months.
Even independent of weight loss, exercise reduces disease risk almost across the board, notably for cardiovascular disease, diabetes, depression & anxiety, and osteoporosis. In observational research, we see that physical activity and the reduction in Heart Disease risk is dose-dependent. More is better. This is where over time, once Jeff has established a habit in easier mode, he could gradually add sessions to meet the Exercise Guidelines of 2.5 to 5 hours of moderate exercise per week. 1.25 - 25 hours for more vigorous exercise.
Parting thoughts
So, exercise should be viewed primarily as a health-promoting tool, while diet is more effective for weight loss. This distinction is critical to help us stay engaged and motivated in the weight loss journey, rather than becoming disillusioned by the perceived inefficacy of our efforts.
If you're already engaged in regular exercise, keep going. Progress gradually to get fitter, stronger, healthier. If at the beginning of your journey, structure the exercise time in your week that's realistic, prioritising the exercise type that supports your health and functional goals, and your enjoyment. The rest of your time and bandwidth can be spent on planning and preparing healthy meals for you and the family.
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