Weight loss is a huge topic these days and there is much debate about how to go about it and what goes into it. To make it super simple- you lose weight when you burn more calories a day than you consume (calorie deficit ).
Lets take a step back and talk about TDEE- total daily energy expenditure. In short, how many calories your body is using a day. Now I'll break that down further so just stay with me.
RMR (resting metabolic rate) is 60-75% of the calories you burn a day. Your RMR is the energy (calories) used to take care of your normal body functions, AKA what your body is doing to survive. This is also where muscle mass comes in. If you have a greater percent of lean body mass (everything in your body that is not fat- so organs, tendons, tissues, muscle etc.) your body will be using more calories to provide for those muscles and therefore burn more calories. Lean body mass can boost your RMR by 7-8% (because of maintaining the muscle mass) so get your training on! So more muscle, more calories burned a day- win, win!
Next up, TEPA (Thermic effect of physical activity). 15-30% of your total daily energy expenditure comes from all physical activity (exercise, shivering, any movement). This one you guys pretty much know. Move more and you'll burn more calories. If you are a sedentary individual you can be buring as litle as 100 calories a day from TEPA, that is not what we want. For extra credit, EPOC (excess post-exercise oxygen consumption). EPOC happens after you've worked out. Your metabolism is still working overtime, even after you have have finished your workout, getting your body back to it's steady state. EPOC can last up to 38 hours and burn and extra 15-25% of calories that you've burned during your workout.
Third and final component of TDEE is TEF (thermic effect of food/feeding). Thermic effect of food is the calories it takes to digest foods; to process, break down and store it in the body. This makes up about 10% of your total daily energy expenditure. This is effected by the number of meals you have, macro-nutrient content (the make up of fats, proteins, and carbohydrates in your meal), calories in the food and your diet.
Calorie Expenditure and Intake
Everything above is what makes up the amount of calories going out (calorie expenditure), now it is up to you on how many calories you're putting in your body. Focus on calorie quantity and quality. If you're staying active and eating right, the weight loss will come.
As a personal trainer, of course I think working out is important and contributes a huge amount to a healthy body, mind and life. But when trying to lose weight, keep a good focus on the rest of your day that does not include your workout. Try to stay active when you can and make the right diet choices. The process can feel slow and frustrating but stick with it and you WILL see results.