At Nourishing Holistic Meal Prep, we often hear people mention the need to “cut back on carbs” to lose weight. As a nutrition-focused business, it’s important for us to address this common belief with empathy and education rather than judgment. Many individuals have been misled into thinking that carbohydrates are inherently fattening, and that focusing solely on reducing them is the key to weight loss.

The low-carb movement has seen cycles of popularity, but what remains is a common perception—that carbs are the enemy. Health-conscious diners frequently opt for bunless burgers, skip the baked potatoes, or feel guilty for enjoying a slice of bread. These tendencies can contribute to an unhealthy relationship with food, leading to feelings of guilt or deprivation.

Over the years, you might have encountered claims such as:

• Carbs raise blood sugar and insulin, causing weight gain.
• Sugars and grains lead to inflammation.
• Unlike fats and proteins, carbs aren’t essential.

While these statements sound straightforward, they oversimplify the complexities of our biology and nutritional needs.

Let’s Break It Down

Do carbohydrates increase insulin levels? Yes, they do.

Does this increase in insulin lead directly to fat gain? Not exactly. In fact, insulin plays a role in signaling fullness, helping to regulate our appetite. Therefore, the notion that insulin alone causes weight gain doesn’t hold up under scrutiny.

Are carbs inflammatory? It depends on the type. Highly processed carbohydrates, like those found in sugary drinks and snacks, can contribute to inflammation. However, whole grains and other minimally processed carbs generally promote health when consumed as part of a balanced diet.

Are carbs less important than proteins and fats? While processed carbs don’t offer much nutritional benefit, whole food sources of carbohydrates are vital for our health. They provide energy, essential nutrients, and fiber that contribute to overall wellness.

Can a low-carb diet aid weight loss? Yes, it can work for some individuals—but it’s not solely because of the carbohydrate restriction, It also comes at the cost of your metabolism which will have long-term negative effects on your health and weight.

Can consuming the right amount of carbs help you feel your best? Absolutely! Carbs are important, especially for those who engage in regular physical activity.

The Challenge of Excessive Carb Restriction

While reducing carbs may be effective for some people in the short term, it’s crucial to understand the potential downsides, particularly for those who lead active lifestyles. Many of us require a certain level of carbohydrates to function optimally. Limiting them too severely over an extended period can lead to a range of negative effects, such as:

• Decreased thyroid output, which can slow metabolism.
• Increased cortisol levels, leading to stress and fatigue.
• Lower testosterone levels, which can impact muscle health.
• Impaired mood and cognitive function, resulting in feelings of lethargy or irritability.
• Muscle breakdown, which defeats the goal of maintaining a healthy body.

In essence, restricting carbohydrates excessively can leave you feeling tired, cranky, and uninspired, while also making it more challenging to achieve long-term weight loss goals.

A Balanced Approach to Nutrition

At Nourishing Holistic Meal Prep, we believe in empowering individuals to develop a healthy relationship with food that embraces balance and variety. Carbohydrates can be a vital component of a nourishing diet when chosen wisely and consumed mindfully. Whole, minimally processed carbohydrates can provide the energy and nutrients your body needs to thrive, enhancing your mood and overall well-being.

So, instead of viewing carbs as an enemy, consider them an important ally in your journey to health. Our focus is on providing delicious, wholesome meals that highlight the benefits of a well-rounded, plant-based approach—because nourishing your body should feel good, both physically and mentally. Let’s embrace food that fuels us, supports our health, and fits our unique lifestyles.

Decreased thyroid

In order to function properly and to maintain an appropriate metabolism, our body produces an important hormone called T3. T3 is the most active thyroid hormone and is incredibly important for blood glucose management and proper metabolic function.

Low T3 levels can lead to a condition called euthyroid sick syndrome, in which people are constantly cold and sluggish. (Imagine your metabolic “body motor” idling at a slower speed.)

A landmark study, known as the Vermont Study, found that T3 is very sensitive to calorie and carbohydrate intake. When calories and carbs are too low, your T3 levels drop.

In addition, the Vermont Study found that another hormone, reverse T3 (rT3), is also sensitive to calorie and carbohydrate intake. Reverse T3, as the name implies, inhibits T3.

Getting enough carbs can lower reverse T3. Not eating enough carbs will increase it, thus blocking the important work of T3.

The Vermont Study is far from alone. Other research confirms that ketogenic (ultra-low carb) diets reduce T3 levels as rapidly as starvation.

Additional studies  show that when calories are held constant (in this case at 2100 calories), reducing carbohydrates from 409 g to 202 g and then to 104 g significantly reduced serum T3 levels (from 91 to 86 to 69 ng/dL respectively).

Finally, French researchers examined four calorically equal diets (2800 calories in this case), lasting 1 week each. Two of these diets contained 250 grams of carbs, which is a fairly typical proportion. The low-carb diet included 71 grams of carbs, and the high-carb diet included 533 grams of carbs.

T3 levels were equal on the normal and high carb diets (ranging from 163.3 to 169.5 ng/100 mL). However, on the low carb diet they fell to 148.6 ng/100 mL on average. And of course, rT3 correspondingly rose on the low carb diet, but not on the standard or high carb diets.

Thyroid hormones are important for more than just weight loss; they also have profound effects on our overall health and energy levels.

Thus, when you don’t eat enough, and/or eat enough carbs while training:

• T3 goes down
• Reverse T3 goes up, further blocking T3
• You feel like crap, and eventually your training sucks

If you’re active, you need adequate energy and carb intakes for a healthy thyroid.

Cortisol up; testosterone down

Research consistently shows that people who exercise regularly need to eat enough carbs or their testosterone will fall while their cortisol levels rise. This is a sure-fire recipe for losing muscle and gaining fat.

Incidentally, it’s also a marker for excessive training stress.

In a study in Life Sciences, men who ate a high carbohydrate versus a low carbohydrate diet for 10 days had higher levels of testosterone and sex hormone binding globulin, and lower levels of cortisol.

A few years later, another study took this research a step further. This time the subjects included men and women who exercised regularly. And in addition to considering the effect of their diet on hormones, researchers put them through some performance tests.

Once again, when the subjects ate a low carb diet, their testosterone (and other anabolic hormones) went down, while their cortisol went up.

And, after following a low carb diet for just three days, only two of the six participants were able to complete the cycling test! Meanwhile, when following the higher carb diet for three days, all six participants were able to complete the test.

In 2010, researchers reconsidered the same question — this time in relation to intense exercise. In this particular study, subjects eating the low carb diet (where 30% of their calories came from carbs) saw a drop of 43% in their testosterone to cortisol ratio. Not good. Meanwhile, the control group (who got 60% of their calories from carbs) saw no change in their testosterone/ cortisol ratios.

Thus:

• inadequate carbohydrate intake can decrease testosterone (which no one wants); and
• increase cortisol (which no one wants); while
• negatively affecting performance (which no one wants).

Carbohydrates and women’s hormones

We now know that eating too low-carb for too long can cause significant disruptions to many hormones.

This seems especially true for women, whose bodies may be more sensitive than men’s to low energy or carbohydrate availability (perhaps because of the evolutionary importance of having enough body fat and nutrients to sustain a pregnancy).

While organs like our gonads or thyroid make hormones, Mission Control of our hormone production system is the central nervous system (CNS), i.e. the brain.

Our hypothalamus and pituitary glands, which sit in the brain, are exquisitely sensitive to things like energy availability and stress (which can include life stress and exercise stress).

The hypothalamus and pituitary work together with other glands such as the adrenal glands. This partnership is often known as the hypothalamic-pituitary-adrenal, or HPA, axis.

Thus, when women don’t eat enough calories or carbohydrate — or even when women eat enough calories but not enough carbohydrate — they face hypothalamic amenorrhea. 

This means disrupted hormones and stopped — or irregular — periods because of the HPA’s response to perceived starvation and stress.

In hypothalamic amenorrhea, hormone levels plummet, and the cascade is felt throughout the system. You end up with low levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estrogen, progesterone, and testosterone.

In addition, we’ve already seen that not eating enough carbohydrate tends to increase cortisol levels. When cortisol rises, it signals your HPA axis to further decrease pituitary activity. Not good.

Your HPA axis regulates functions such as stress response, mood, digestion, immune system, libido, metabolism and energy levels.

And your pituitary in particular is responsible for synthesizing and secreting growth hormone, thyroid stimulating hormone, prolactin, LH, FSH and other incredibly important hormones.

With all this said, here’s the takeaway message: Many women try to eat low-carb, wanting to be healthier.

Yet because low-carb diets can significantly disrupt hormone production, women with too-low carb intakes — especially active women — can face:

• a stopped or irregular menstrual cycle;
• lowered fertility;
• hypoglycemia and blood sugar swings;
• more body fat (especially around the middle);
• loss of bone density;
• anxiety, depression, and other mental health issues;
• chronic inflammation and worse chronic pain;
• chronic fatigue and disrupted sleep; and
• a host of other chronic problems…

…ironically, this is the exact opposite of what they wanted in the first place.

Muscle loss

When we think about building muscle, we usually think of protein. But research shows that lowering carb intake can affect your muscle mass even if protein remained constant.

In other words, even if you’re guzzling protein shakes or eating steak 5 times a day, you could be losing muscle if you aren’t getting enough carbs.

A recent study from the Netherlands compared three diets:

• a high carb diet (85% carbs);
• a medium carb diet (44% carbs); and
• a low carb diet (2% carbs).

All diets had the same total calories and the same amount of protein — 15%. (Yes, a little low, but more or less adequate.)

The result? For starters, pretty consistent with other research.

• T3 levels and reverse T3 levels stayed the same with high and moderate carbohydrate intake.
• T3 levels and reverse T3 went down on the low-carb diet.

But here’s the interesting wrinkle. In this study, the researchers also measured urinary nitrogen excretion to see how the diets affected protein breakdown.

In this case, the low carb diet increased muscle breakdown, because severely low carbs lowered insulin levels.

Again, you’d assume that protein intake would determine muscle breakdown. And you might assume — based on what you’ve heard — that having higher insulin is always “bad”.

In fact, insulin is crucial for building muscle.

When you get enough carbs to meet your needs, you replenish muscle glycogen and create an anabolic (building-up) hormonal environment. You get strong and buff. That’s good.

Conversely, when you don’t eat enough carbohydrate, muscle glycogen is depleted and a catabolic (breaking-down) hormonal environment is created, which means more protein breakdown and less protein synthesis. This means slower muscle growth — or even muscle loss.

The Role of Carbohydrates

Avoiding carbohydrates can lead to a range of issues, such as lowered T3 hormone levels, disrupted cortisol to testosterone ratios, and potential interference with hormone balance. This could contribute to muscle loss and hinder muscle gains—certainly not ideal for anyone looking to feel their best!

However, it’s a common misconception that low-carb diets are universally superior for fat loss. While it might seem logical that minimizing carbs would keep insulin levels low and lead to rapid weight loss, the reality is more complex.

Many individuals initially see weight loss on low-carb diets; however, this quick success is often primarily water weight and glycogen depletion rather than significant fat loss. When we look at long-term studies, the evidence suggests that differences between low-carb diets and other balanced diets tend to even out over time.

The Importance of Protein

It’s also important to highlight that many studies comparing low-carb diets with other protocols often do not control for protein intake. This means participants on low-carb diets frequently end up consuming more protein, which has its own benefits:

• Protein has a higher thermic effect, meaning our bodies burn more calories digesting it.
• It promotes feelings of fullness, helping to manage appetite.
• It supports the retention of lean muscle mass.

In fact, research shows that when protein intake is matched, those following a moderate carbohydrate diet feel better and often achieve similar weight loss results to those on stricter low-carb diets. In one study, participants consuming moderate carbohydrates reported improved mood and lost a comparable amount of weight, with a slight tendency toward greater fat loss.

Both dietary groups improved their insulin sensitivity, but the low-carb group also encountered increases in LDL cholesterol and inflammatory markers, leading to feelings of decreased energy. This highlights the importance of quality over quantity when it comes to macronutrient intake.

Understanding Individual Needs

At Nourishing Holistic Meal Prep, we believe that there is no one-size-fits-all approach to nutrition. Carbohydrate needs vary widely among individuals. While many people thrive on a balanced intake of all macronutrients, some may benefit from adjusting their carbohydrate levels based on their lifestyle and goals.

• Most people perform best with a reasonable amount of carbohydrates.
• A minority may thrive on higher carb levels, such as athletes involved in high-endurance sports.
• Some individuals, particularly those with certain medical conditions or metabolic challenges, may find a temporary lower-carb approach helpful.

For athletes, individual responses to carbohydrate intake can vary widely. Some may feel great on a low-carb regimen, while others could notice declines in performance, especially in high-intensity moments. It’s essential to personalize nutrition to ensure optimal energy levels and performance, particularly for those engaged in demanding physical activities.

The Importance of Balance

Fad diets often lead us astray, tempting us to pursue extremes in our eating habits. The truth is that both low-carb and overly restrictive diets can leave individuals feeling deprived, unhappy, and ultimately lead to an unsustainable pattern of eating.

At Nourishing Holistic Meal Prep, we champion a balanced approach, encouraging our clients to nurture their bodies with an appropriate mix of lean proteins, quality carbohydrates, and healthy fats. Our recommendations are supported by research and our experiences with clients, helping to establish sustainable habits that foster long-term health.

In summary, most of us are likely to look, feel, and perform our best when we embrace a well-rounded diet. Rather than viewing carbs as an adversary, let’s celebrate them as a vital component of a nourishing diet that supports our well-being and enriches our life.

Finding Balance with Carbohydrates

We believe in keeping things simple when it comes to nutrition. Here are some key principles to guide your approach:

• Avoid Over-Restriction: Don’t overly restrict your food choices or overthink your meals.
• Skip the “Carb Math”: Focus on enjoying your food rather than worrying about counting carbs or calories.
• Embrace Variety: Incorporate a wide range of minimally processed, whole, and fresh foods into your diet.
• Listen to Your Body: Pay attention to how you look, feel, and perform as you eat. Use this personal data to guide your choices.
• Trust Your Experience: Make decisions based on your unique body and experiences, rather than what others tell you you “should” do.
• Celebrate Carbs: For most active individuals, carbohydrates are your friend and an important source of energy!

By following these principles, you can create a nourishing and enjoyable relationship with food that supports your health and well-being.

Additional PubMed Resources