Everywhere you go, anyone and everyone has an opinion on nutrition. Low carb, high carb, high protein, low protein, low fat/no fat, Atkins, HCG, Paleo, Gluten Free, and the list goes on.
Whether you do a Google Search, read fitness magazines, read a blog, or Facebook post, you are guaranteed to walk away confused and frustrated. So the question is, what really works for losing weight permanently and healthily?
One of the big nutrition mistakes most people make when they want to lose weight/body fat and keep it off for good, is they DON’T EAT ENOUGH CALORIES to lose body fat and keep it off.
To most of us, this sounds crazy and a bit counter intuitive. How would eating more calories lead to losing more body fat?
It all comes down to two things, metabolism and hormones.
In theory, if you burn more calories than you consume you will lose weight. In order to lose 1 pound of body fat a week you require a deficit of 3500 calories (500 calories/ day). This can be achieved through proper nutrition or exercise, or ideally, a combination of both.
However, there is always a point of diminishing returns when creating a calorie deficit, and where too much can actually slow down and maybe even reverse your progress. Let me give you an example. Let’s say between your basal metabolic rate, weekly exercise, non exercise calorie burning activity, and digestion of food you burn an average of 2500 calories a day.
In order to lose 1 pound a week, you only need to eat 2000 a day. Well hey, why not eat 1000 calories a day and then you get to lose 3 pounds a week, and create a 1500 calorie deficit each day.
Better yet, let’s just eat 500 calories a day, and we get to lose 4 pounds a week, and a 2000-calorie deficit a day!!!
In theory, this makes complete sense, but practically speaking something completely different happens. While the math may be sound, hormonally and metabolically this strategy will not work long term.
To help you understand why low calories are not a sound strategy metabolically and hormonally, it is important to understand our evolution and the biological mechanisms that helped us survive thousands of years ago.
The human body is biologically designed to hang on to and store fat, especially during times of famine and starvation. This explains why we were able to survive without food for long periods of time, thousands of years ago. And evolve to where we are at today in a society of food abundance.
Thousands of years ago food abundance was an unfathomable concept. Humans hunted and gathered to meet their nutritional needs.
Food supply was always unpredictable. It was not uncommon for human beings to go weeks and even months without any food. To survive, and deal with this feast and famine cycle, the body’s metabolism would slow down to conserve and save energy during periods of famine. To survive with little to no food, energy conservation and reducing energy expenditure (calorie burning) was extremely important. As calories and fat stores were limited, energy output needed to be at a minimum each day to stay alive. Without minimizing energy expenditure, survival would be at stake as your body will burn calories from muscle and fat stores, and you could eventually die.
This biological mechanism of lowering metabolism when food supply, and without burning up all of our fat and muscle tissue, allowed us to survive long periods of time of famine.
How does this apply to dieting and not eating enough calories? Well, your body can’t distinguish between actual starvation, and “restrictive dieting” or “ low calories”. To your body it’s one in the same.
If the situation is considered “one in the same”, then the response from your body will be “ the same” as well.
When we wish to lose fat, it needs to happen slowly and intelligently. Notice I said lose fat, and not just weight. There is a big difference between the two. Fat loss is losing actual body fat. Where weight loss could mean losing some fat, water, glycogen, and muscle. The goal should always be the former, as losing body fat will enhance your health and overall wellbeing. Just losing “weight” does not equate to improved health. Especially if it is in the form of muscle loss, which lowers metabolism making weight maintenance and future weight loss more difficult.
If your calories are too low, relative to your bodyweight, height, and how much physical activity you do, there can be negative consequences both short and long term for your metabolism.
You can only lose body fat so fast. There will always be a point of diminishing returns, and a point where you are tipping the scale towards muscle loss and putting metabolic health at risk. Attempting to lose weight quickly, and creating too large of a calorie deficit will always work against your biology and the built in mechanisms we all have to combat low calories and “starvation”. Whether starvation is real or because of a restrictive unsustainable diet.
Here is what happens when you restrict calories too much, and how it can actually lead to increased weight gain over time.
1. When you lower calories for too long, your body starts to perceive this as starvation. So it lowers it’s metabolic rate, meaning you burn less calories at rest, and less calories overall to converse energy and survive.
Unfortunately this allows you to fewer calories you burn at rest, making weight gain a whole lot easier.
Compare someone who has a metabolic rate of 1000 calories a day, compared to someone with 3000. Who have more leeway to eat more calories to maintain and even lose weight? The answer, of course, is the person with a metabolic rate of 3000 calories a day.
2. Since you are on low calories, you will unconsciously move less during non-exercise activity, and scale back on your intensity during your workouts.
This is a subtle way in which your body conserves more energy from exercise and non-exercise activity. All of this this is due to metabolic slowdown from the low calories. In effect, this leads to less overall calorie burning during throughout the days, weeks, and months to follow.
If your calorie intake is too low to support your goals, your bodyweight, and height, there are 3 hormones that will be impacted in the process and make fat loss much more difficult long term.
Specifically your T3 and T4 hormones. Many research studies have shown that when your calories are too low for too long, thyroid output and activity slows down. You secrete and produce less T3 and T4, which have a direct affect on metabolic rate. As thyroid output slow, metabolic rate and the number of calories you burn at rest will decrease over time.
As you eat less calories your leptin levels lower. Leptin triggers satiation giving you a feeling of fullness and helps to regulate hunger. As leptin levels lower, your body gets the signal that there is a danger (hunger) and an emergency around the corner.
This is one of the reason we to get hungrier as we lose weight, as lower leptin levels are associated with eating less calories, but also with carrying less body fat. In theory, the more body fat you carry, the higher your leptin levels tend to be, which assists in feeling satiated. However, there is a fine line here, where too much body fat can contribute to “leptin resistance”, and you never feel satiated despite carrying high levels of body fat.
As leptin levels drop, this can cause overeating and overindulging, as hunger is no longer inhibited. This is why you will see people partake in a post diet binge, or binge during their diet, especially on very calorie restrictive diets. This is all due to the fact that leptin is suppressed to unsustainable levels.
A great example of this is if you have gone all day without eating or eat small amount of food during the day. When you get to dinner, your brain has already triggered hunger and low leptin levels, and you tend to overeat and overindulged in more food than if you ate consistently throughout the day. This is one of the major reasons why eating consistently throughout the day is key to losing body fat.
This example now leads us to our next hormone… Ghrelin.
Ghrelin works in the opposite direction of leptin, and actually stimulates appetite. When ghrelin levels are elevated, your appetite increases and you eat more. When you eat a meal and begin to digest your food, ghrelin levels lower, and the feeling of hunger goes away. Another reason why low calories are unsustainable, and actually lead to increased weight gain down the road.
Elevated ghrelin levels from too low calories cause you to want to more as your appetite is stimulated. And the higher ghrelin goes, the more calories you will eat. Compound that with the fact your metabolism has down regulated from lower calories, and this is a recipe for rapid weight gain over the long term.
This is exactly why people who go on an extreme diet with are heavier down the road, and end up regaining their weight back plus more.
To lower ghrelin levels, and take away that feeling of hunger, your body needs to eat. And it will eat more calories, the longer and higher ghrelin levels are.
This is why it is so important to eat enough calories to lose weight, and to also create a small sustainable calorie deficit each week.
Large calorie deficits work short term, but are extremely difficult to maintain over the long haul. As you now know, this is due to this hormonal regulation within your body, primarily from leptin and ghrelin that regulates hunger and satiation. And also through reducing metabolic rate during periods of low calories.
The main point to keep in mind is this: As calories lower, your leptin levels lower signalling hunger and a lack of satiation, which then increases levels of ghrelin which then stimulates appetite causing you to eat.
So now that we know all of this, the question is, how many calories should I eat each day to lose weight healthily and sustainably?
There are many ways to figure this number out. You can eye ball portion sizes. You can use your hand as a guide to gauge how much food to eat, which can be practical.
Or you can figure out the exact amount of calories you need to eat in a day, and go from there. I recommend this option, as it ensures you aren’t overeating or under eating on calories, and you are getting an exact number to work with.
Initially, this can be a bit tedious and time consuming. But once you figure it out, and create a plan around it, implementing it will be easy.
I would always recommended seeing a trainer who has extensive knowledge and credentials in nutrition, a nutritionist, or a dietician to help you create a plan like this.
Probably the most accurate way to figure out daily calories is to use the Harris Benedict Equation.
This equation calculates your resting metabolic rate using your height, weight, gender, and age. All of which have an impact on your metabolism.
Simply guessing how many calories you require doesn’t take into account individual metabolic needs and would not be recommended. With the “guessing” approach, there is a good chance you will either under eat or overeat, both of which impede long term fat loss.
Here is the Harris Benedict equation
RMR: 66.5= (13.75 x weight in kilograms) + (5.0 x height in centimeters) – (6.76 x age in years)
RMR: 655 + (9.56 x weight in kilograms) + (1.85 x height in centimeters) – (4.68 x age in years)
Let’s take Sue who is 5’5, 40 years of age, and 160lbs. To figure out her daily caloric intake to lose body fat, we would need to plug these numbers in to the formula.
RMR: 655 + (9.56 x 72.73 kg) + (1.85 x 167.5 cm) – (4.68 x 40) = 1474.4 calories/ day.
Now we need to factor in non-exercise activity, as well as actual exercise.
Is our example, we are going to say Sue is active 3-5 days a week; we will multiply 1474.4 by 1.5= 2211.6 calories.
This is the average amount of calories Sue would burn in a day if we factored in resting metabolic rate, and all of her physical activity.
Now we need to subtract calories to create a “deficit” to lose body fat. A recommended calorie deficit is something that should be sustainable, and won’t adversely impact metabolism and the hormonal mechanisms explained earlier.
For this example, a calorie deficit of 500-750 calories a day would be sustainable.
This would mean Sue could expect fat loss of 1-1.5 lbs. per week. Anything more than this, and she would risk negatively impacting metabolism, increasing the hormonal response from leptin and ghrelin, and significantly increase hunger cues and appetite which would make following a diet much more difficult.
So to start, Sue would need to eat between 1461.6- 1711.6 calories a day to lose weight sustainably.
Or to round 1500-1700 calories a day.
While this method of calorie calculation is the most accurate, another way you can figure this number out is my multiplying your bodyweight by 10. If Sue did this, she would have landed right in the middle of what we recommended at 1600 calories (for men, you would take bodyweight x 12).
Sue would never want to go below 1500 calories a day, or else she would risk metabolic down-regulation and an increased hormonal response from leptin and ghrelin. This could lead to increased weight gain down the road, as explained earlier.
So as you can see, fat loss does not require you to starve and go hungry. In fact, you need to eat more than what you would think to lose body fat, and to “stoke” that metabolic fire.
Keep in mind that as you lose weight, hunger cues will naturally increase, but they should not be to the point of being unbearable. As you get leaner and closer to your goal weight, strategies like “refeed days” can help with mitigating intense hunger cues if they arise. But this is an advanced strategy that should only be used (for most people) once they are on those last 5-10lbs, and have developed consistent, proper eating habits.
At the end of the day, the main takeaway point is that you need to eat enough calories to lose weight healthily, and to properly support metabolism and your hormones over the long term.
If you have tracked your calories and your portions with a food journal, and notice you are under eating based on your numbers, then you may need to increase calories.
For example, if you are only 1000 calories a day, and need to eat 1500 calories to lose weight, increase this slowly over time. Your body needs time to adapt to the increased calories, and time to increase your metabolic rate.
Start by increasing your calories by 200-250 every 4-6 weeks, until you reach 1500 or your set number.
This will ensure body fat gain stays to a minimum. Initially you may gain a little bit but long term you will reset and increase your metabolic rate to normal levels. This will help increase fat loss and help you maintain your goal weight over the long term.
If you have been consistently eating lower than the recommended calories for a long period of time (Over 1-2 years), and have not seen consistent weight loss, and have in fact gained weight, then you may need to see a professional to have your thyroid examined and may need a different protocol to improve your metabolic rate.
In part 2 of the article, we will expand on our discussion or the proper amount of calories to lose body fat and what ratio of carbohydrates, proteins, and fats are appropriate for someone with these goals.
Always here to inspire and motivate you,
David Macdonald and the Vitality Fitness Team