Please understand that online calculators get you in the ballpark, but not much more than that. You will always have to fine-tune the numbers based on trial and error. However, the process is not that scary.
Your BMR (Basal Metabolic Rate) or more accurately RMR (Resting Metabolic Rate) is a measure of how many calories your body uses when doing nothing at all. I.e. sleeping or laying down.
This is where everyone needs to start. The truth is, unless you are a paraplegic, you are going to use more than the basic RMR throughout the day. The way online calculators make the adjustment is based off of an activity multiplier.
An activity multiplier is an estimated increase in calories needed to support your normal activities. When thinking about this multiplier, it's all about your average for the whole week.
Using the information you provided and this calorie calculator, we can start to zero in on what is a more reasonable number of Calories to hit:
- BMR (activity multiplier set to 1) comes out to 1424 Cal/day
- Using "Lightly Active"* the Calories to maintain weight are 1958 Cal/day
- In order to lose 0.5kg / week (healthy rate) you would need to have an average of 1458 Cal/day
So let's discuss why we picked these numbers, so it's more helpful in the long run:
- I chose "Lightly Active" over "Moderately Active" because you are new to strength training, so you aren't using as many calories as someone who has been at it a while.
- There are 3500 Calories in a pound of fat (just under 0.5 kg), so when you average that over a week, you need to drop about 500 Calories a day.
So using the numbers we are working with, a reasonable starting point to preserve muscle mass and emphasize fat burning would be this:
- Total Calories: 1450 Cal
- 0.83 g protein per lb body weight: 115 g (doesn't have to be exact)
- 20% calories from fat: 32 g (20% of 1450 is 290 Cal, 9 Cal / gram fat = 32 g)
- All the rest as carbs: 187 g carbohydrates (4 Cal / gram protein + calories in fat leaves 748 Cal, 4 Cal / gram carbs is 187)
If you eat this every day, it will average out to about 0.5 kg lost a week. There are some strategies that help. For example, emphasize carbs and protein before, during and after training (15-20g protein each, with 3-4x as many carbs). This should give you energy for your training when you need it, and better prevent more fat storage. (Based on information from the Sport Nutrition Encyclopedia by Josh Thigpen et al).
Some recent studies show that cardio does not burn muscle as much as previously thought, and it really depends on the mode of cardio. For example, the high impact of running has more affect on muscle building than riding a bike. Swimming, ellipticals, stationary bikes, or even going outside and riding a bike are all great ways to do the long slow cardio in a way that complements strength training.
Adjusting as you lose
As long as you are losing weight at a comfortable rate, you can keep up the status quo. However below are a few guidelines on how to adjust if weight loss is too fast or not fast enough:
- If you are losing weight too fast, or you are done with the fat loss increase your diet by 100-200 Calories and re-evaluate at the end of the week.
- Take measurements in addition to weighing yourself on a scale. You might not lose weight, or even gain a little one week, but lose inches. That's your body building some lean mass and burning fat.
- If measurements are going up and the scale is going up/staying the same, decrease your diet by 100-200 Calories and re-evaluate at the end of the week.
You may find that you might need to shuffle the macros a little to keep momentum where you want it. When you are satisfied with your progress, gradually increase to maintenance levels and keep the exercise up. You shouldn't make jumps any more than 200 Calories at a time, and no more frequently than once a week.
Food choices make a big difference
In general, try to aim for foods that are not very inflammatory. This happens to work out well for what we understand as "healthy foods":
- Fruits and Vegetables
- High fiber carb sources like oatmeal and quinoa
- Meats and eggs
- Generally anything that's not highly processed
You'll find that many of these foods are low density. In other words, not a lot of Calories for the portion you are eating. That's a great thing when you are on a diet since it helps prevent the feeling of being "punished", and you actually may feel like you could never eat all the food you have outlined for you.
I recommend keeping things simple. Don't try to adjust up or down for training/non-training days. However, if you choose to do that, keep in mind the average for the week should be hitting the targets for your calories and macros.
There's a lot of right answers, but the best answer is something you can do habitually.