Welcome to part three in my series on the cost of weight loss!
In part one we took a look at how some of my blood markers changed with regards to weight loss.
In part two we discussed how my metabolic rate slowed despite eating a lot of food (not necessarily calories) with very little restriction.
In part three I wanted to talk about some practical things you can do in your own weight loss journey to fight against a slowing of metabolic rate. There is nothing we can do in order to completely eliminate the slowing of your metabolism during a weight loss diet but there are certainly things you can do that will make it worse.
As we have discussed in part two of this series as you lose weight you will have some degree of metabolic adaptation. Part of this has to do with a shift in hormones, but part of it also has to do with the fact you just weigh less. In general the less you weigh, the fewer calories you burn. That is all OK, it is normal. For most people you probably don’t even need to worry about this.
As always, it’s best that you focus on the things you can control, with that said there are some things you can influence when it comes to metabolic adaptation and the slowing of your metabolism…that is what we will address in this blog post.
Slow And Steady Wins The Race
The #1 thing you can do to make metabolic adaptation worse during a weight loss diet is to be overly aggressive with how quickly you are losing weight. The faster you lose weight the more of a shock it will be to your body, so your body will pull out all the stops in order to make your metabolism match your food intake (\/, 2023). If you take a gentler approach to weight loss you can avoid shocking your body. Aim for 0.5-1lb of weight loss per week on average, that is a nice slow trend and avoid stressing your body into immediately putting the breaks on your weight loss. It might take you longer to reach your goal, but as we will discuss later this can lead to more success in maintaining your new body weight once you do.
Even if you do take a slow approach to your weight loss it is inevitable that you will likely experience the dreaded weight loss plateau. When you see this happen, don’t fret. The first thing I suggest you do is NOTHING AT ALL. Don’t change a thing.
Let me say that again….NEVER CHANGE ANYTHING IF YOU FAIL TO LOSE WEIGHT over the course of a week!
Remember we are shooting for losing 0.5-1lb per week ON AVERAGE. That means some weeks you will lose more, and some weeks you will lose less, none, or even gain some weight. However over the course of MONTHS your average should be 0.5-1lb of weight loss per week. Also keep in mind that as you approach your ideal body weight, weight loss will tend to slow down. The leaner you are the harder it will be to lose weight, so give yourself some grace when you are getting close to your goal. Celebrate the progress you have made thus far, keep your eye on the goal and stay the course.
So how long should you wait to make a change if you don’t see the scale moving?
I would give it a month at least. If after a month you have seen no weight loss you probably need to reassess where you are at and if something has changed. Most people’s first instinct when they reach this point is to slash more calories, do some kind of crazy fast, change diets, cut out more carbs or fats, or exercise harder. However that is not where I would look first.
Remember weight loss has to do with more than just the food you eat…sleep, stress, and activity all play a role as well. So when you are assessing why your weight loss has stalled you need to take into account changes in all parts of your lifestyle. For example, you might realize that you have been under a tremendous amount of stress over the past month and it’s been affecting your sleep. In this case the answer is not to make some kind of drastic change to your diet but instead try and address the new stressor…or you may need to put your weight loss on hold while you wait for the stressor to pass.
Diet Breaks
The other solution to navigating a stall in your weight loss for an extended period of time is potentially eating more food.
How does that make sense?
Your body is very good at adapting to a chronic stimulus…and a weight loss diet is just that, a chronic stimulus.
This is exactly what metabolic adaptation is, it’s an effort by your body to adapt to the signal you are sending to it by eating less food. Its goal is to match your caloric expenditure with its intake so that it makes sure it doesn’t run out of energy.
So could interrupting a weight loss diet with a period of time eating more calories help mitigate metabolic adaptation?
The research suggests that it might.
In one study (Intermittent Energy Restriction Improves Weight Loss Efficiency in Obese Men: The MATADOR Study, 2017) researchers had one group of participants alternate between 2 weeks of eating in a deficit with 2 weeks of eating at maintenance calories, and another group continuously eat at a deficit for the entire time. Because of the 2 weeks of maintenance the diet break group had to diet for 30 weeks while the continuous group dieted for 16 weeks. At the end of the study the diet break group lost more fat AND did not experience as much of a slow down in their metabolism.
In addition to potentially mitigating the metabolic slowdown from a consistent caloric deficit, breaking up your diet with periods of eating more foods has countless mental benefits. Knowing you aren’t consistently restricted and allowing yourself some more freedom in the foods you are eating can be a nice break from the metal fatigue of always having to be thinking about the foods you are eating. This can have a huge impact on the sustainability of a long term fat loss goal.
So how often and how long should you take breaks from your diet? How should you eat during these breaks?
First let’s address the easier of those two questions, how you should eat.
In general you are going to eat the exact same foods, but just more of them. You will have more of the fats and carbs you are currently eating. You can choose to add the calories from all fats, all carbs, or a mixture of both, it doesn’t matter. All we are trying to do is give your body and your brain a break from the diet.
As far as how often and how long you should take a break from your diet, that is a matter of personal preference. Some people like to implement weekly diet breaks, while others like to implement diet breaks over the course of weeks or months.
If you choose to do more frequent diet breaks the length of those breaks will be shorter, if you choose to do less frequent diet breaks they will be longer. For example if you do a weekly diet break you might just choose 1-2 days during the week and eat at maintenance calories. If you choose to do a diet break every few months you might spend 2 weeks eating at maintenance.
One suggestion I have no matter what strategy you use is to plan diet breaks around social engagements.
If you have a wedding coming up it might make sense to choose that day to have a diet break. If you are doing longer term diet breaks it might make sense to have a diet break around a vacation or around the holidays for example…periods of time where it would be more enjoyable to eat more food.
For more information on diet breaks you check out the blog post I wrote on the topic.
Macros
The final thing to pay attention to in terms of mitigating metabolic adaptation are your macros.
As always when we talk about macros, protein is king. This is particularly true in terms of someone who is in a caloric deficit because eating less calories than your body requires to maintain its weight makes you more susceptible to muscle loss. While some muscle loss is inevitable when trying to lose fat, we want to minimize it as much as possible. If we don’t offset the loss of muscle during a fat loss diet we could potentially lose just as much muscle as fat and at the end of the diet be the exact same body composition.
In other words your weight might be down, but you are still the body fat percentage! For example let’s say you start your diet at 30% body fat (which is considered obese for males and females). At the end of the diet you have lost 10 pounds but 5 of those pounds were fat and the other 5 were muscle.
Guess what?
You might weigh 10 pounds less…but you are still 30% body fat because the ratio of fat to muscle is still the same! From a health perspective you are still obese!
In addition, the loss of muscle mass is often correlated with slowing of your metabolism (Collateral Fattening in Body Composition Autoregulation: Its Determinants and Significance for Obesity Predisposition, 2018). Meaning the more muscle mass you lose while dieting means it’s more likely your metabolism is slower than if you were able to maintain that muscle.
Finally the loss of muscle mass while dieting is associated with what is called “fat overshooting” post diet. What is commonly observed in research is that those people who lost the most muscle during a weight loss diet have the potential to regain more fat than they lost (Weight Cycling of Athletes and Subsequent Weight Gain in Middleage, n.d.). This is what is known as “fat overshooting”. In other words it means if you lose too much muscle while dieting you are more likely to not only gain back all the fat you lost during the diet BUT MORE! Oh and by the way, you don’t gain back all the muscle you lost…putting you at a worse body composition than when you started the diet!
I hope that all that is enough to convince you to try to maintain as much muscle as possible while dieting. As we mentioned protein is key to this, but the question becomes how much? My usual recommendation across the board is 1g per pound (2.2g per kilogram) of body weight (or ideal body weight if you have a lot of weight to lose). However there is some evidence that those recommendations may be a tad low when trying to lose weight. According to a review paper on resistance trained athletes in a caloric deficit you may need to be eating 1.05g – 1.4g per pound (2.3-31.g per kilogram) of body weight (Brown, 2013).
I would say you should be eating at least 1g per pound of body weight, but if you want to eat more, up to 1.5g per pound of body weight, it’s unlikely to be detrimental.
In fact eating more protein than you technically need can have two additional benefits when dieting.
First, protein in its whole food form (not protein powders) is one of the most satiating foods you can eat, helping you feel fuller longer (Protein, Weight Management, and Satiety, n.d.).
Second, protein costs the most energy to digest. This means our body burns the most amount of calories trying to digest protein (A High-Protein Diet for Reducing Body Fat: Mechanisms and Possible Caveats, 2014). If your metabolism is going to slow, it makes sense to eat foods that cost the most amount of calories to digest in order to offset the slowing of your metabolic rate so protein can be a big help in that area.
One final point on maintaining muscle mass while dieting, eating enough protein will not maintain muscle mass on its own. In addition to eating enough protein you need to be doing 2-3 strength training sessions per week. If you need some guidance on strength training you can check out my blog post here.
OK with protein out of the way, what about fats and carbs, are there scenarios where those macronutrients can make the effects of metabolic adaptation worse?
Let’s start with fats. Drastic cuts to fat intake have been linked to drops in testosterone in males (Pietinen, n.d.) and drops in estradiol and progesterone in females (Tritchler, n.d.). We also know that prolonged caloric restriction and low body fat percentage is associated with lower sex hormones in males and females. This means that if you are going on a diet, there is a chance your sex hormones may be negatively affected just by being in a caloric deficit for a long period of time, however that effect can be exacerbated if you are eating too little fat.
In addition to maintaining sex hormones, we also need some level of fat in order to take in enough essential fatty acids and promote the absorption of vitamins which require fat to be absorbed by the body.
Then there is the fact that fat adds some level of enjoyment to food, the perfect example is eating a boneless skinless chicken breast to a bone in skin on chicken thigh…most people will choose the chicken thigh every time.
With all that said, most people should not be going below 1.3-1.5g of fat per pound (0.6-0.7g of fat per kilogram) of body weight.
Finally we come to the topic of carbohydrates. Unlike proteins or fats, carbohydrates are not a required macronutrient. However we should not interpret that statement to mean that everyone can be optimally healthy eating 0 carbohydrates. In particular there is a lot of anecdotal evidence showing that low carb diets can negatively affect thyroid function. One potential mechanism for why is that insulin is needed to convert one thyroid hormone to the other and insulin can be quite low when you have been restricting carbohydrates. Just like we talked about with fats and sex hormones, lower thyroid hormones can be part of dieting for a long period of time so we don’t want to exacerbate the lowering of thyroid hormones by eating too few carbohydrates.
In addition, low carb diets can be viewed as another stressor to the body. And when the body is already in a stressed state because you are dieting for a long period of time, it can be the straw that breaks the camel’s back. If you can relieve this stressor by including some amount of carbohydrates in your diet that is going to be a win for your overall health.
Finally, carbohydrates are going to be beneficial from the perspective of performance in the gym. I talked at length about how important protein is for maintaining muscle mass during a diet, but I also mentioned that you need to resistance train in addition to eating enough protein to have any hope of minimizing muscle loss. Carbs can be quite beneficial from a resistance training point of view because they will allow you to exercise with more intensity and therefore send a louder signal to your body that you need that muscle around and to not get rid of it.
So how many carbs should you eat?
It really comes down to how many calories you have left after you account for your protein and required/desired amount of fat. Basically you figure out your protein and fat calories, subtract them from your total calories you need to intake to keep yourself in a caloric deficit and then what you have left is the calories you can consume from carbs. Divide those calories by 4 (1g of carbs has 4 calories) and you have how many grams of carbs you can eat a day.
Here is an example to make things clearer.
Let’s say to lose weight at a sustainable pace you can eat 2000 calories a day. Based on the protein guidelines above you need to eat 150g of protein and 75 grams of fat per day. To get your protein and fat calories you would multiply 150 by 4 and 75 by 9 and add those two numbers together.
(150 *4) + (75 * 9) = 1275 calories from protein and fat
Now subtract 1275 from 2000 and you will be left with how many calories you can consume from carbs.
2000-1275 = 725 calories from carbs
Now divide 745 calories by 4 to get how many grams of carbs you can eat.
725 / 4 = 181 grams of cabs
One final tip with carbs is to consume a majority of them around your exercise session in order to reap the most benefit out of them from a performance standpoint.
In summary the act of eating in a caloric deficit for an extended period of time will cause your body to try and adapt to the lower calories. This is natural, and can be reversed by eating more calories once you reach your desired body composition. However, we can also mitigate the severity of the metabolic adaptation by taking a gradual approach to weight loss, breaking up your caloric deficit by occasionally spending some time eating maintenance calories, and eating enough protein and resistance training to try and maintain as much muscle mass as possible.
As for my own body composition data as a result of my caloric deficit and what my plan is moving forward to return to maintenance calories and reverse my own metabolic adaptation, I will share those details in my next blog post. To be the first to know when I publish my next blog post be sure to sign up my newsletter using the form below and I will email you as soon as it is available.
References
\/. (2023, June 16). YouTube. Retrieved November 21, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2822830/
Brown, S. R. (2013, October 2). A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. PubMed. Retrieved November 21, 2023, from https://pubmed.ncbi.nlm.nih.gov/24092765/
Collateral fattening in body composition autoregulation: its determinants and significance for obesity predisposition. (2018, March 20). NCBI. Retrieved November 21, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5945583/
A high-protein diet for reducing body fat: mechanisms and possible caveats. (2014, November 19). NCBI. Retrieved November 27, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4258944/
Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. (2017, September 19). NCBI. Retrieved November 21, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5803575/
Pietinen, P. (n.d.). Diet and serum sex hormones in healthy men. PubMed. Retrieved November 25, 2023, from https://pubmed.ncbi.nlm.nih.gov/6538617/
Protein, weight management, and satiety. (n.d.). PubMed. Retrieved November 27, 2023, from https://pubmed.ncbi.nlm.nih.gov/18469287/
Tritchler, D. (n.d.). Effects of a low-fat high-carbohydrate diet on plasma sex hormones in premenopausal women: results from a randomized controlled trial. Canadian Diet and Breast Cancer Prevention Study Group. PubMed. Retrieved November 25, 2023, from https://pubmed.ncbi.nlm.nih.gov/9218745/
Weight cycling of athletes and subsequent weight gain in middleage. (n.d.). PubMed. Retrieved November 21, 2023, from https://pubmed.ncbi.nlm.nih.gov/16568134/