From the 1940s onwards, the low-fat diet was an ideology that Americans could get on board with. Until recently. There’s been a noticeable shift in the past decade or so, starting with an embracement of the “low carbohydrate diet” (paired with an increase in fat intake), but fat is something that still equals ‘bad’ for many. But what is fat, exactly? Is it bad? And does it affect our hormones, those mission-critical messengers that keep us running and in good health? These are some of the questions we’ll be answering in this article, in particular the question of what fats you should consume more of, and the impact they have on other health markers. Let’s dive in.
- What are fats?
- What are hormones?
- Do fats impact hormones?
- The symbiotic relationship between fats and hormones
What are fats?
“Fat” is a small word for a bigger concept; it encompasses three things:
- Dietary fats
- Structural fats, and
- Body fat
Let’s tackle each of these in turn.
Dietary fat
Dietary fat is essential to your general health and wellbeing, and it comes in four main forms:
- Saturated fat
- Trans fats
- Monounsaturated fats
- Polyunsaturated fats
Fats that have little nutritional value and that are correlated with higher levels of LDL cholesterol (“bad” cholesterol) are saturated fats and trans fats. These tend to be solid at room temperature. Monounsaturated fats and polyunsaturated fats, on the other hand, tend to be liquid at room temperature. According to the American Heart Association, eating an overall diet that has higher monounsaturated fats and polyunsaturated fats can work to lower the levels of cholesterol that trans fats and saturated fat are associated with.
Examples of saturated fats are often found in animal products (though there are a select number of plant-desired saturated fats) and they include: butter, ghee, lard, coconut oil, and palm oil. Health organizations like the NHS recommend offsetting the amount of saturated fats with other types of fats, in particular omega-3s. For instance, as opposed to having butter on toast, consider getting your dose of fat through sardines on toast, or salmon with your salad.
Unsaturated fats are commonly found in foods from plants, which is why when we look at examples of unsaturated fats we find items like: vegetable oils, nuts, and seeds. Besides reducing levels of LDL in the blood, they are also associated with easing inflammation and stabilizing heart rhythms. Unsaturated fats can be further broken down into two groups we mentioned above: monounsaturated fats and polyunsaturated fats.
Great sources of monounsaturated fats are:
- Avocados
- Olive oil
- Canola oil
- Peanut oil
- Almonds
- Pecans
- Hazelnuts
- Pumpkin seeds
- Sesame seeds
What we love about this list is that a lot of these items are easy to work into everyday: avocado on toast or in your salad, using canola oil to cook your eggs instead of butter, adding sesame seeds as a mid-afternoon snack – the list goes on!
Potentially even better for you on a molecular level, we have polyunsaturated fats, which are also often deprived from plants, as well as fish. Examples include:
- Sunflower oil
- Soybean oil
- Flaxseed oil
- Canola oil (a good source of both poly and monounsaturated fats!)
- Fish
What’s interesting about that last item, fish, is that it is full of omega 3 fats. These are unique in that the body can’t make these, so they must come from food. Plant sources of omega 3 include flax seeds, walnuts, and canola oil, while eating fish 2 to 3 times a week should also get you a healthy dose of omega-3s!
Structural fats
We usually think of fat when it comes to food, but actually fats can also be a type of lipid. This is a category of molecules “united by their inability to mix well with water.” Different lipids have different structures, but essentially they are great for essential functions like storing energy, providing insulation, making up cell membranes, and providing building blocks for hormones.
Lipids are used directly or synthesized indirectly from fats present in the diet. There are a number of ways this breakdown can happen, but know that the main biological functions of lipids include storing energy (while they can also be broken down to release energy). Furthermore, they make the structural components of cell membranes, and help signal molecules in the body.
Body fat
Did you know there’s more than one type of fat in the body? Unfortunately, some of these types are associated with negative health outcomes, but fat doesn’t automatically equal bad. In fact, without fat on our bodies, we would not be able to live. In other words, while having a high body fat percentage can yield negative health effects, so too can having too low of a body fat percentage.
The types of fat in the body can be broken down into the following categories: white, brown, and beige. White fat is what we think of when we think of fat. It is white cells that are stored underneath the skin, and this energy can be utilized at a later date. White fat is also known to play an important role in the function of hormones, in particular estrogen, leptin (which stimulates feelings of hunger), insulin, cortisol (the stress hormone), and growth hormone. Brown fat is what babies have (although adults retain a small percentage in the neck and shoulders), and it burns fatty acids to keep you warm. Finally, beige fat is a new discovery and something scientists are trying to learn more about: beige fat cells might also burn fat rather than store it under certain conditions, prompted by the release of certain hormones and enzymes, in particular those released when stressed or cold. The question of whether white fat may be converted to beige fat in certain circumstances is interesting, and there is much more to be researched in this space.
Having a healthy body fat percentage is essential to the following functions:
- Temperature regulation
- Balanced hormone levels
- Better reproductive health
- Vitamin storage
- Balanced blood sugar
- Healthy metabolism
What are hormones?
We’ve dedicated an entire article to understanding hormonal health, but in a nutshell: hormones are chemical messengers. Common examples you may have heard of include estrogen and testosterone, while more ‘unlikely’ hormones (but hormones nonetheless) include: insulin and corticosteroid.
According to Johns Hopkins Medical, the endocrine system uses hormones to control and coordinate many functions inside the body, including your:
- Internal metabolism (aka homeostasis)
- Energy levels
- Reproduction
- Growth and development
- Response to injury and stress
Specifically, their role is to fulfill one of the following two functions:
- Communicating between two endocrine glands
In this scenario, one gland releases a hormone which prompts another gland to change the levels of hormone it is releasing in turn. A great example of this symbiotic relationship is the pituitary gland and the thyroid gland: the pituitary releases TSH, and in turn, the thyroid gland modifies its levels of T3 and T4.
- Communicating between an endocrine gland and an organ
In this situation, hormones communicate with organs directly. For instance, your pancreas releases insulin, and the liver works to both store and manufacture glucose.
Do fats impact hormones?
Okay, so we’ve explained what fats do (both in your diet and in your body) and what hormones do (so much!): but do these two things interact? The answer is absolutely.
First of all, fats are the building blocks of hormones, so for that reason they have a dependent relationship. More so than that, research indicates that there is a symbiotic relationship in which hormones can also impact fats (ie in the form of changing lipid profiles). For instance, in one animal study, sources of omega 3 had an “effective role” in improving lipid and hormonal profiles, reducing blood glucose, and improving weight gain in rats with PCOS. In particular, after supplementation of synthetic omega-3 fatty acids, the levels of testosterone, luteinizing hormone, and insulin were decreased in rats fed vegetable-based oils.
Another study, this time in women, released in 2016 indicates that dietary fat intake could be linked to improved fertility. In particular, intake of polyunsaturated fatty acids (shortened to PUFAs) was “associated with very small increases in testosterone concentrations in healthy women and that increased docosapentaenoic acid was associated with a lower risk of anovulation.” In other words: dietary fat intake could have an impact on ovulation, and therefore on one’s ability to get pregnant. The authors cite other small studies that showed greater fat intake was associated with improved menstrual cycle characteristics, but that due to some limitations on these studies, more research needed to be conducted when it comes to dietary fat intake on hormone profile and its impact on menstrual cycle function. That being said, implications for women’s reproductive health from this study alone are difficult to deduce: more research and funding is certainly needed in this area.
Finally, we turn to the question of the relationship between the endocrine system and fatty acids. In one review in the journal BioFactors, the author argues that hormones affect the metabolism of fatty acids and the fatty acid composition of tissue lipids. Polyunsaturated fatty acids decrease insulin resistance, while trans fats and saturated fats can lead to an “increase in insulin resistance.”
Takeaways from the research
Clearly, fat has been demonized for a long time, but there is much more nuisance on this topic than the typical ‘fat is bad, carbs are good’ paradigm would suggest.
- We need fats
First of all, fat plays an essential role in our bodies on multiple levels, performing many essential functions, including helping us keep warm, storing energy, providing the building blocks for hormones, and of course, providing amazing tastes in our food. In fact, the main complaint of an ultra low-fat diet (considered <15% of total calorie intake) is that it doesn’t taste very good. In that sense – fat is amazing.
- We should be careful about what types of fats we consume
Now that we know not all fats are created equal, though, it is worth trying to reduce the levels of saturated fats we consume, owing to their association with negative health outcomes, and instead focus on consuming more monounsaturated fats and polyunsaturated fats.
Remember, monounsaturated fats and polyunsaturated fats typically come from plant-based sources (think olive oil, sunflower oil, pumpkin seeds, and sunflower seeds, with the exception of coconut oil as a plant-based saturated fat), while saturated fats and trans fat typically come from animal products. Now does this mean you need to cut out all saturated fats? Absolutely not! Butter, ghee, and coconut oil all have important places in many dishes and can be cultural staples. However, it may be worth exploring how to limit your intake of saturated fats, thanks to their positive association with LDL cholesterol (ie ‘bad’ cholesterol), and try to increase your intake of unsaturated fats.
Not only are they likely good for reducing insulin resistance, reducing inflammation, and lowering levels of ‘bad’ cholesterol in the blood, they also work to add much needed flavor to some of our favorite meals.
Some easy recommendations for getting more unsaturated fat in your diet include: avocado on toast, salmon on a bed of salad, chia or flax seeds in your smoothie, canola or sunflower oil in your baking (as a replacement for butter), and adding nuts as a snack or to your favorite meals where possible. And when in doubt? Turn to the Mediterranean diet: this diet has been around for centuries, and places emphasis on eating whole-fat foods, vegetables and fruit, and fish, while limiting the amount of processed foods and animal products in your diet. More on the PCOS plate and how it derives from the Mediterranean diet to offer amazing health benefits here!
- Omega-3s are ultra-important to our health
Finally, let’s talk about omega-3s. Our bodies don’t make these, so it’s essential we get them from our diets. There are three main types of omega-3. EPAs and DHAs come from fish, and ALAs come from vegetable oils and nuts, as well as seeds. The body uses ALAs for energy, and conversion to those all-important EPAs and DHAs is limited, so if you are vegan, it may be worth checking with your doctor or seeking the advice of a registered dietitian to make sure you’re getting the right balance of omega 3s. If you do consume fish, then this chart produced by Harvard Health may be useful in finding out the easiest ways you can work more omega-3s into your diet.
Interested in reading more? Check out this article on following a Mediterranean diet.
Allara Health provides personalized treatment for hormonal, metabolic & gynecological conditions that utilizes a holistic plan that merges nutrition, lifestyle, medication and supplementation, and ongoing, expert support to heal your body.