For decades the idea of calories in, calories out has been the model for weight management. This is often called the Energy Balance Model. This model’s philosophy is that weight management is controlled by the balance of the calories we eat and the balance of calories we burn. On the surface, this makes sense, but I believe, and research has shown, that it is actually much more complicated than that.
Why calories in, calories out may fail you:
Restricting calories can place the body in starvation mode
Consuming calories lower than what your body needs to survive will slow your metabolic rate
Low-calorie diets lead to rebound weight gain
Your unique genetics play a role in how you absorb and process your food which can affect your weight management strategy
Caloric quality matters
Let’s think about it, obviously eating 2,000 calories of jelly beans is not the same as eating 2,000 calories of whole, natural fuel with a balance of carbohydrates, proteins and fats. But, under the Energy Balance Model, as long as the person who eats 2,000 calories of jelly beans burns 2,000 calories during the day their weight will remain stable. Is this true? According to the NIH (National Institutes of Health), there is far more to it. In the latest evaluation (https://doi.org/10.1093/ajcn/nqac031) there is a difference in the metabolic effects of consuming a calorie from a refined carbohydrate (like candy or a sugary soda) than consuming a calorie from a lean protein source (such as chicken or fish). This is where the Carbohydrate Insulin Model (CIM) comes into play. This model looks at whether significant spikes in blood sugar cause a bolus release of insulin which can have a rebound effect and cause blood sugar to crash which can effectively cause hunger and fatigue. That insulin spike also causes your body to store more fat. Anytime insulin is released, your body shuts off the signal to burn fat. All the highly processed, high-sugar foods consumed in our Western Diet are taxing the body hormonally, predisposing our bodies to store fat while also rearing our brain to want more of those foods and leaving us less satiated by balanced foods. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7529959/#)
Higher glycemic foods (simple carbohydrates, high sugar, highly processed foods) trigger a hormonal response (increase in insulin) that pushes calories to fat tissues. This increase in insulin is a signal to your body to store as much energy as fat as it can and not burn any fat. Repeating this process over and over leads to insulin resistance which leads to obesity and potentially diabetes.
Beyond insulin, there are additional hormones that respond differently based on the type of food consumed. Ghrelin, which is your hunger hormone, is temporarily suppressed in the presence of any type of food consumption. If your meal is primarily simple carbohydrates where the sugar hits the bloodstream and leaves quickly (no fiber, high-sugar foods such as candy, sugary soda), ghrelin begins to increase within 2 hours and it rises quickly and will be above where it started leaving you hungrier than prior to eating. On the other hand, if you eat fats or protein, your ghrelin will be low for 4 hours and then has a gradual climb, not a stark rise like you will see with simple carbs. Ensuring your carbohydrates are more complex (containing fiber) will give you a more sustained ghrelin response than simple carbohydrates. Overall carbohydrate dominant or carbohydrate-heavy meals can lead to hunger more quickly than a balanced meal containing a healthy mix of proteins, fats and carbohydrates.
Ghrelin’s counterpart is leptin. Leptin is your fullness or satiety signal. Carbohydrates release a stronger initial satiety signal than fat or protein-heavy meals. That may sound like a good thing, but leptin is released from fat cells and as you gain weight and increase your fat cells, more leptin will be released and eventually, just like insulin, your body becomes resistant to high hormone levels and starts to ignore it. In effect, what happens is that your brain essentially loses that signal to stop eating. Interestingly, protein does lead to increased satiety levels while not causing the surge in leptin.
Calorie for calorie; protein, fat, and complex carbohydrates eaten together will lead to the greatest balance of satisfaction and hunger-supression with the least amount of fat storage.
If the philosophy is that you need to burn more calories than you are taking in, then why would a lower-calorie diet cause these reactions? Following a calorie level that is lower than your body needs to function appropriately will lead to strong metabolic inefficiency and the greater the inefficiency the stronger the pull on your body to get back to or stay at your original weight. As you do begin to lose weight your appetite will begin to increase, this is a starvation response. Your body is trying to protect itself. You will also suffer lower energy levels which can lead to less activity which will in effect cause you to burn fewer calories and this is where the vicious cycle of yo-yo dieting can begin. The more you restrict calories the lower your metabolic rate will be and the lower calories your body will burn on a daily basis, thus leading to more weight gain.
Whenever we eat, our metabolic rate increases during that time period and the amount it increases differs based on
what we eat. The number of calories burned by digestion is relatively small, it is only about 10% of your daily metabolic rate, but it is interesting to know your body works harder to break down protein than it does to break down carbohydrates or fats. For every gram of protein you eat, your body uses about 25% of the calories for digestion. This means that if you eat 100 calories worth of protein, your body will use about 25 of those calories to break it down. In comparison, if you eat 100 calories worth of carbohydrates, your body will use about 12-15% of those calories for digestion. This is a minor difference, but it is important to note the differences in digestibility.
And of course, genetics plays a role in all of this, some are more susceptible to that insulin surge after carbohydrates than others. And genetics also plays a part in the number of calories one person absorbs versus another; therefore, if this is you then you will need to adjust to those unique needs. As you can see in this page from a sample genetics report, some of us have a harder time maintaining or losing weight than others and looking at your DNA can tell us where we need to adjust to assist you in meeting your goals. Your individual genetic needs are definitely one piece of this intricate puzzle.
All in all, big picture, could it possibly be that diet quality, whole, natural foods with a healthy macronutrient balance including protein, healthy fats, healthy carbohydrates with fiber, that will keep your blood sugar steady in combination with monitoring calorie input versus calorie expenditure may be the keys to weight management success?
So, if all this seems like a lot and you are wondering where to focus first?
Taking a few key points from my "Optimal Health Checklist", which are the areas I ensure are dialed in first with all my clients, can guide you on where to start:
Ensure you are eating enough- focus on at least 500 calories per meal (this is very individual depending on your goals, activity and this is where personalization is key)
Reach your protein threshold- focus on at least 30 grams of protein per meal
Reach that perfect macros mix- always ensure you have protein and fiber along with any carbohydrates you are consuming and focus on healthy fats focus on whole, unprocessed or minimally processed foods
Hydrate, hydrate, hydrate-- consume at least half your body weight in fluid ounces per day
Don't eat too late- close your eating window at least 2-3 hours before you go to sleep
Click below to grab this useful resource.
If you want to dive a bit deeper, you can also grab my "How to Build
a Healthy Meal" resource. This can help you get a little more specific on how to create a healthy meal and why each macronutrient is important.
And finally, if you are wanting to go even deeper, book a FREE 15 min exploratory call to discuss how I can help you reach any health and wellness goals you may have.
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Polidori D, Sanghvi A, Seeley RJ, Hall KD. How Strongly Does Appetite Counter Weight Loss? Quantification of the Feedback Control of Human Energy Intake. Obesity (Silver Spring). 2016 Nov;24(11):2289-2295. doi: 10.1002/oby.21653. PMID: 27804272; PMCID: PMC5108589.
Reed GW, Hill JO. Measuring the thermic effect of food. Am J Clin Nutr. 1996 Feb;63(2):164-9. doi: 10.1093/ajcn/63.2.164. PMID: 8561055.
Reed GW, Hill JO. Measuring the thermic effect of food. Am J Clin Nutr. 1996 Feb;63(2):164-9. doi: 10.1093/ajcn/63.2.164. PMID: 8561055.
Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. Int J Obes (Lond). 2010 Oct;34 Suppl 1(0 1):S47-55. doi: 10.1038/ijo.2010.184. PMID: 20935667; PMCID: PMC3673773.
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