CICO vs Hormones

Calories in vs calories out (CICO) is a popular dietary method that aims to help people regulate body weight through diet and other lifestyle modifications.

However, there are numerous ways to implement the CICO method, and each may have different effects on your overall health, especially your hormonal balance.

Moreover, certain hormonal issues may significantly hamper your metabolic health, which makes CICO more challenging and much less effective.

Therefore, we have decided to delve into the scientific underpinnings of the CICO method, examining how it interacts with the body’s hormonal systems and vice versa – which hormonal issues and therapies may optimize its effectiveness in achieving your goals.

What is the CICO Diet Method?

Here is what you should know about the main terms in CICO, based on scientific evidence:

Your “calories in” is your energy/food intake. It depends on your appetite and food choices. Having an increased appetite and choosing more caloric foods can increase your caloric intake and vice versa.
“Calories out” stands for total daily energy expenditure (TDEE).

Your TDEE depends primarily on basal metabolic rate (BMR). This is the amount of energy your body needs to maintain the functions of all organs and tissues. It accounts for about 50-70% of TDEE and depends primarily on your body weight, but also body composition, hormonal balance, and overall health.

The other components of your TDEE include:

Exercise activity thermogenesis (EAT) refers to the calories burned during planned physical activities, like workouts or sports.
Non-exercise activity thermogenesis (NEAT) includes the energy expended for everything that is not sleeping, eating, or sports-like exercise. For example, walking to work, typing, performing yard work, standing up, or even fidgeting.
Diet-induced thermogenesis (DIT), aka thermic effect of food, is the energy you need for digestion, absorption, and disposal of ingested food. It is influenced by the type of food you eat, with protein having a higher thermic effect compared to carbohydrates. Further, fats have the lowest thermic effect. Processed foods also have lower DIT.

The aim of CICO is to help you take control of your weight by modifying your caloric intake and caloric expenditure.

For example, someone who would like to gain weight should increase their caloric intake (i.e., eat more high-calorie foods) and reduce their caloric expenditure (exercise less).

In contrast, if you aim to lose weight, you have to reduce your energy intake (the best way is to eat more low-calorie foods) and increase your energy expenditure (moving more, exercising more, eating less processed foods).

Is CICO Scientifically Proven?

The available scientific evidence consistently shows that a person’s weight gain or loss primarily depends on their energy balance, i.e., the comparison between caloric intake and caloric expenditure.

For example, large clinical trials confirm that various diets, including low-fat and low-carb options, lead to similar weight loss. That is when the caloric deficit—the difference between intake and expenditure—is the same.

Therefore, researchers suggest that the CICO principle always works for weight loss as long as it creates a negative energy balance, aka a calorie deficit.

However, some people may find it challenging to achieve success with CICO for several reasons:

Despite the abundance of calorie trackers, estimating calorie intake can be difficult. Especially when purchasing ready-made meals without clearly listed nutritional values per serving, as it is often impossible to accurately determine the amount of added fat or other ingredients.
Merely filling your calorie quota with any available or desired food until reaching your caloric goal can lead to increased hunger and adverse metabolic effects.
It may be challenging to correctly estimate your energy needs. Numerous formulas and calculators exist, but none are 100% accurate, as your TDEE also depends on genetics, dietary habits, overall health, and other individual factors.

Moreover, even if weight loss is successful, losing or gaining weight may not necessarily reflect an improvement in body composition.

Whether weight loss results from fat or muscle loss depends on your food choices, the balance of proteins, fats, and carbs, and your level of physical activity.

Therefore, choosing nutritious options such as whole foods and balancing every meal with adequate protein and fiber is extremely important while following the CICO diet method.

Do Hormones Affect CICO?

Hormones may significantly affect the balance of your calories in vs calories out. More specifically, some hormones may affect the energy expenditure of your body (calories out), while others may also interact with appetite levels and thus food intake (calories in).

Hormones that may increase your caloric output may include:

Testosterone – the main male sex hormone helps increase energy expenditure due to the fact that it stimulates processes in the body that burn extra calories such as muscle growth. The increase in lean mass also results in higher BMR. Research suggests that other naturally-occurring male sex hormones (androgens) such as DHEA may also increase energy expenditure.
Growth hormone (GH) – GH also appears to increase energy expenditure, and the margin appears to be greater than what can be explained with lean mass gains alone. Thus, GH may also stimulate tissue metabolism and the activity of other glands such as the thyroid.
Thyroid hormones – have a well-known effect on increasing basal metabolism and adaptive thermogenesis, as they interact with a wide range of other hormones, body heat production, organ and tissue metabolism, etc.
Glucagon – Albeit best known for its ability to increase blood glucose via glucose production and glycogen breakdown, studies suggest that glucagon may also lower body weight by increasing metabolic rate. It is produced by the pancreas.
Epinephrine and Norepinephrine – Often referred to as adrenaline and noradrenaline, these are released by the adrenal glands in response to stress. They may increase your heart rate, blood pressure, and fat breakdown, and can significantly boost your metabolic rate, albeit for a short period of time.

Hormones that may reduce your caloric intake may include:

Leptin – Produced by adipose tissue, leptin sends signals to your brain to suppress appetite. As your fat stores increase, leptin levels rise to further reduce appetite.
Insulin – Secreted by the pancreas, insulin helps your body regulate glucose levels in the blood and also has effects on hunger and satiety. Higher levels of insulin, which occur after you eat, are associated with reduced appetite.

Does a Calorie Deficit Affect Your Hormones?

Interestingly, hormones may be influenced by how much you eat, what you eat, and even when you eat it.

When applying the CICO method and reducing your energy intake to lose weight, this may affect several hormones, including:

Тestosterone – Studies suggest that calorie restriction may lead to lower T levels. That is especially true when the “calories in” are cut entirely from either fats or carbohydrates.
Thyroid hormones – Energy restriction by reducing your “calories in” may decrease your T3 levels, which is the main active thyroid hormone.
Ghrelin – the hunger hormone is produced when your stomach is empty. Thus it increases as the amount of food which you eat decreases, making you hungrier.
IGF-1 – insulin-like growth factor-1 is the main mediator of the anabolic effects of GH. While GH may increase during calorie restriction and especially fasting, this blunts the response of the tissues towards it, which results in lower IGF-1 levels.

What is the Effect of TRT on CICO?

Testosterone replacement therapy (TRT) involves the use of exogenous T that helps normalize the levels of the hormone in the body.

It is a highly effective therapy for managing symptoms in patients with low T, who also often suffer from loss of muscle mass and fat gain.

Studies suggest that TRT does not lead to an immediate effect on the balance between calories in vs calories out. According to one trial, there was no increase in energy expenditure within the first 3 weeks of T therapy.

Instead, researchers report that TRT affects calorie expenditure, primarily by increasing lean body mass, more specifically muscle mass. The increase in muscle mass is reported to become most notable after at least 12–16 weeks of TRT and stabilize at 6–12 months, although it may marginally continue over years.

One notable trial has reported that the energy expenditure in healthy men increased by 7% after 12 weeks of TRT, and the increase was “for the most part” explained by the increase in muscle mass.

Furthermore, other studies suggest that the increase in “calories out” is maintained even after cessation of TRT, as long as the increase in lean body mass is also maintained.

With that being said, supraphysiological doses of TRT may also have some hypermetabolic effects, such as stimulating the metabolism of fat tissue by increasing the levels of beta-adrenergic receptors to release the stored and reducing the activity of lipoprotein lipase (LPL). Blocking the LPL enzyme prevents the fat from returning inside fat cells.

High doses of TRT may also induce rapid muscle growth, which is also an energy-intensive process and may contribute to higher TDEE.

What is the Impact of rhGH on CICO?

Recombinant human growth hormone (rhGH) therapy involves the injection of exogenous GH that helps restore hormonal balance.

It is primarily indicated for use in men and women with growth hormone deficiency (GHD) – a condition that often manifests with muscle wasting and abdominal fat gain.

Studies suggest that once rhGH therapy is initiated, it helps normalize muscle mass, abdominal fat, and metabolic rate in GHD patients. More specifically, the mean BMR of the patients increased from 1246 to 1539 kcals/day which is over 20% increase.

About 80% of this increase in energy expenditure was reported to be explained by the increase in lean muscle mass.

Other factors that may explain the increase in “calories out” during hGH therapy may include the increase in the metabolism of fat, especially visceral fat, and also the indirect action of the therapy on other hormones.

The GH has depot-specific effects which target primarily abdominal and visceral fat. Thus, therapy with rhGH may speed up the metabolism in these tissues and contribute to increased energy expenditure.

According to studies, you may experience a significant reduction in the amount of abdominal subcutaneous fat as soon as 6 weeks after starting HGH therapy.

Strategies for Balancing CICO and Hormonal Health

To appropriately implement the CICO diet method into your regime, it is important to understand that simply reducing your “calories in” by eating less or following a restrictive diet may have a negative impact on your hormonal health.

For example, reducing your “calories in” via strategies such as fasting may have negative effects on the balance of your thyroid hormones. Studies suggest that frequent and prolonged fasting can dramatically reduce both T3 and T4. Therefore, it may be better to maintain regular food intake while reducing total “calories in” for weight loss.

Another common mistake when applying the CICO method is reducing the amount of food without improving food quality. Consuming small amounts of food can elevate ghrelin levels and lead to uncontrollable hunger.

This is why it is recommended to choose low-calorie but high-volume foods when reducing your “calories in” such as more fresh fruits, veggies, etc. They help create volume in the stomach and reduce hunger.

Furthermore, reducing your energy intake for weight loss is a great strategy to improve T levels, especially if you have excess body fat.

But males who attempt to cut their calories by dramatically reducing their intake of fats, or alternatively – avoiding all carbohydrates, may do more harm than good for their testosterone levels. Studies suggest that both low-fat and low-carb diets appear to decrease T. Thus, a more balanced decrease in both fats and carbs may minimize this.

The recommended ratio of calories coming from fats and carbs in a weight loss diet is anywhere between 45-60% for carbs and 20-35% for fats. That is, as long as the remaining 20% of your total “calories in” is filled up by proteins.

With that being said, some people with hormonal imbalances may have trouble losing weight even when strictly following the CICO method. That may be due to hormonal deficiencies such as GHD or low T.

In such instances, we highly recommend visiting a licensed medical doctor, who can help diagnose your condition and assign appropriate therapies, such as TRT or hGH if needed.