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How Weight Gain and Hormones are Related

posted by

Dr. Kimberly Boileau

Weight Loss
Hormonal Health

I find insightful solutions to hormone burnout, helping you restore energy, gain control over your weight and harness the hormonal superpowers you are made to enjoy.

Hi, I'm Dr. Kim

Have you ever wondered if weight gain was related to your hormones? The most common answer is that we take in too many calories. But most of the world has hinged its understanding of weight on some flimsy science. Between 1971 and 2000, the rise of obesity rates is associated with a daily caloric increase of about 200-300 calories¹, and that made it easy to blame the epidemic on calories. A good scientist knows that correlation is not causation, and calories might have very little to do with your weight after all.

Here are the Five Lies your Doctor Told You About Your Weight


THE TRUTH: The number of calories you consume tells your body how many calories to burn.

Experiments and experience have proven this to be true, and it means that the calories you take in, and the calories you burn depend on one another. In other words, – increasing calories triggers calories to be burned and vice versa. In studies where calories are reduced by ~30 percent, calories burned were also reduced by… wait for it… 30 percent!⁵ The result is minimal weight loss.

Recently, the relationship between weight gain and calorie consumption has been reexamined.²In 1990 to 2010, the National Health and Nutrition Examination Survey (NHANES) in the United States finds that although the rate of obesity increased by 0.37 percent per year, caloric intake was unchanged. The data suggest no association between increased calorie consumption and weight gain.

weight gain and hormones lab test button

Since the British obesity epidemic largely ran parallel to North America’s, data from that population would also be useful. But once again, neither increased caloric intake nor dietary fat correlated to obesity.³ The daily calorie intake slightly decreased, even as obesity rates increased. What HAD changed was WHERE they were getting their calories from.

We often imagine this simple equation: Calories In – Calories Out = Body Fat

We make this calculation assuming that ‘calories out’ is constant (aside from exercise), and we get this idea from a whole scientific community who invoke the law of thermodynamics to support this model. The First Law of Thermodynamics states that energy can neither be created nor destroyed in an isolated system. In an article in the New York Times in 2012, Dr. Jules Hirsch explains:

“There is an inflexible law of physics—energy taken in must exactly equal the number of calories leaving the system when fat storage is unchanged. Calories leave the system when food is used to fuel the body. To lower fat content—reduce obesity—one must reduce calories taken in, or increase the output by increasing activity, or both. This is true whether calories come from pumpkins or peanuts or pâté de foie gras.” ¹⁵

But the human body is not an isolated system! Stay with me here.

The body can use excess energy (calories) in an endless number of ways. It can produce:

  • heat
  • protein
  • bone
  • muscle
  • improved cognition
  • increased heart rate
  • Increase digestion

If we eat 200 extra calories today, nothing keeps the body from using those calories for heat, motivating us to exercise or building new tissues. Yet, we think so much about how many calories we eat and we assume the only change in output is from exercise.

This calorie equation we use assumes that the body doesn’t regulate fat cells and that we can control what we gain and lose. But if every other body system is regulated, why should this be?

The truth is that hormones regulate fat balance. We cannot decide how much energy to store as fat and how much to use for new muscle formation, even when we exercise. Could it be that our weight gain and hormones are related? So many studies have failed to show promise for the calories in-calories out model, that it seems more reasonable that excess fat is a problem of distribution of energy. To find out if your hormones are storing excess energy, get the guide to find out what levels I test in my office and what they mean.

The Calorie equation is easy to study. Take some people, reduce their intake and watch the pounds fall off. Done. Right?

Apparently not.

In several prestigious US Universities, a series of ‘starvation diets’ were extensively studied over the last 100 years, and the results were obvious from the first. When the intake of calories was reduced by 20-30%, the body used 20-30% fewer calories. 

Between 1944 and 1945, Dr. Ancel Keys performed the Minnesota Starvation Experiment⁶, a very detailed study attempting to understand the effects of widespread starvation after World War II.⁷

The study took thirty-six young, healthy, normal men who received a standard diet of 3200 calories per day. Their calories were reduced by half over the next six months, and the diet consisted almost entirely of starchy vegetables, bread, and pasta. Their caloric expenditure was over 3000 calories daily.⁸ The men also underwent a caloric rehabilitation phase where their caloric intake increased to normal. 

The ‘semi-starving’ men experienced profound physical and psychological changes. Their metabolic rate dropped by 40 percent. There was a very significant decrease in muscle strength & endurance, heart rate, body temperature & blood pressure. They lost hair, their nails grew brittle and they became completely obsessed with food.

So how much weight did they lose? If the calories in-calories out model is correct, the men would have lost an average of 78 pounds, but the actual weight loss was only 37 pounds. That’s less than half of the expected loss!

Let’s say you weighed 100 pounds. If you reduced your daily calorie intake by 500 calories, we assume that you lose 1 pound of fat per week. Does that mean that in 100 weeks, we would lose 100 pounds and weigh nothing? Of course not. The body must, at some point, reduce its caloric expenditure to meet the lower caloric intake. 

The body’s reaction seems logical when we reflect on the findings. In to survive, the body reduced its expenditure of energy when its available fuel decreased.

The body adapts to lower caloric output very quickly, and it persists long-term. Any serial dieter will tell you that more and more severe caloric restriction is required to continue losing weight. 

Sound familiar?

The studies demonstrate two more lies;


THE TRUTH: You expend calories depending on how many you take in.


THE TRUTH: Your metabolic rate changes when you change your intake.

But what happened to their weight after the semi-starvation period?

Once the subjects started the recovery period, they regained the weight in about twelve weeks. What’s more – their bodyweight increased until it was higher than baseline!

Consider a typical dieter. Shortly after she restricts calories to 1500 per day, a dieter’s metabolism slows to a daily output of only 1500 calories. This slow metabolic rate persists beyond the length of the diet – sometimes for years! So with any intake above 1500 (even if it’s lower than her original caloric intake), all her weight comes rushing back—as fat. Is she lacking willpower? No, her body has stacked the odds against her. What is most unfair is that all of this was documented 100 years ago!


THE TRUTH: Your body can make it nearly impossible to resist food.

Just because it’s your hand that feeds you doesn’t mean we control it. Our hormones largely govern our decision to eat and when to stop.

Imagine trying to eat a whole steak after you’ve stuffed yourself full of a turkey at a holiday dinner. It probably wouldn’t seem that appealing, would it? The smell of steak grilling might make you feel a bit sick. Consider when you’re hungry – does the steak smell delicious? The smell isn’t different, but your body’s response is. 

In 2006, the National Institutes of Health published a massive dietary study, arguably the most telling nutritional study ever done. It was a randomized controlled trial called the Women’s Health Initiative Dietary Modification Trial, and it followed 50,000 post-menopausal women. They followed a low-fat diet like the Dietary Guidelines for Americans, (very similar to Canada’s current food guide).¹² The trial was attempting to confirm that the low-fat diet would create weight loss, heart health benefits, and cancer reduction.

The study ran for 7.5 years, and the intervention group showed a reduction of 342 calories per day average. The control group continues to eat the same high-calorie and high-fat diet as before.

By the end of the study, the intervention group weighed the same as the control group. The average waist to hip ratio increased in the intervention group, so they had gained more fat!

How could this be? 

As we have seen, reducing calories will prompt the body to reduce calorie expenditure, as a way of adapting and regaining homeostasis. But also, the hormonal signals that produce hunger will increase. 

Weight loss results in reduced metabolic rate and increased hunger. In this way, we see that weight gain is a hormonal disorder, not a caloric one. Is this happening to you? This free weight loss lab guide will tell you what to look for.

Another study in 2011 demonstrated this perfectly. A dramatic calorie reduction to 500 calories produced significant weight loss quickly, but when given a low-fat maintenance diet, participants gained almost half the weight back! The subject’s hormone testing revealed the hormone of hunger – ghrelin was increased. What’s more – this hormone was still elevated more than a year after the initial diet.¹⁴


THE TRUTH: Calories from different foods tell your body to store fat or burn it.

Although it seems so logical, calories from different foods do not cause weight gain equally. 

Does a tablespoon of butter create the same metabolic response as a tablespoon of sugar? Not even close. Sugars increase the blood sugar and insulin levels, and fats do not. They affect the hormones differently.

I suppose you’re thinking that the answer lies in the glycemic index, the measure of blood sugar response to a given food? Low-glycemic diets have indeed shown some benefit for those with diabetes, but there is a WHOLE OTHER HORMONE STORY that few people are telling, and its simpler than you think.

So what makes us gain weight?

Hormones do. In my experience, weight gain in otherwise healthy people is almost always due to one of two situations:

  1. Thyroid imbalance
  2. Insulin Imbalance

The great news is that both are treatable! But the first step is finding out which is the factor that’s affecting you. To find out, grab this free guide and stay tuned for more on naturopathic treatments for weight loss, and how weight gain and hormoens are related.

weight gain and hormones lab test button


1. Wright JD, Kennedy-Stephenson J, Wang CY, McDowell MA, Johnson CL. Trends in intake of energy and macronutrients: United States, 1971—2000. CDC MMWR Weekly. 2004 Feb 6; 53(4):80–2.

2. Ladabaum U et al. Obesity, abdominal obesity, physical activity, and caloric intake in US adults: 1988 to 2010. Am J Med. 2014 Aug; 127(8):717–27.

3. Griffith R, Lluberas R, Luhrmann M. Gluttony in England? Long-term change in diet. The Institute for Fiscal Studies. 2013. Available from: Accessed 2019 Aug 6.

5. Benedict F. Human vitality and efficiency under prolonged restricted diet. Carnegie Institute of Washington; 1919. Available from: Accessed 2019 Aug 6.

6. Keys A, Brožek J, Henschel A, Mickelsen O, Taylor HL. The biology of human starvation (2 volumes). MINNE ed. St. Paul, MN: University of Minnesota Press; 1950.

7. Guetzkow HG, Bowman PH. Men and hunger: a psychological manual for relief workers 1946. Elgin, IL: Brethren Publishing House; 1946.

8. Kalm LM, Semba RD. They starved so that others be better fed: remembering Ancel Keys and the Minnesota Experiment. J Nutr. 2005 Jun 1; 135(6):1347–52.

10. Pieri J. Men starve in Minnesota. Life. 1945 Jul 30; 19(5):43–6.

11. Rosenbaum et al. Long-term persistence of adaptive thermogenesis in subjects who have maintained a reduced body weight. Am J Clin Nutr. 2008 Oct; 88(4):906–12.

12. Howard BV et al. Low fat dietary pattern and weight change over 7 years: the Women’s Health Initiative Dietary Modification Trial. JAMA. 2006 Jan 4; 295(1):39–49.

13. Bell Kristine et al. Efficacy of carbohydrate counting in type 1 diabetes: a systematic review and meta-analysis. The Lancet 2014 Feb 1; 2(2):133-140. Available from Accessed 2019 Aug 6.

14. Suminthran P. Long-term persistence of hormonal adaptations to weight loss. N Engl J Med. 2011 Oct 27; 365(17):1597–604.

15. Jason Fung, MD. “The Obesity Code.” Apple Books.

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