Dietary Fat – Health Risk or Super-Nutrient?

Where protein is widely acclaimed and carbohydrate maligned and misunderstood, fat is the ‘chameleon’ macronutrient. One day it’s an under-rated super-nutrient, the next its linked to a variety of serious diseases.

The ‘black or white’, either it’s good or bad, framing doesn’t help anyone. It simply encourages us to take a position on one side of a non-existent fence. We end up vigorously defending ‘our’ side, whilst shouting the ‘other’ side down.

The simple reality is that fat is many things, good and not so good. It’s an essential macronutrient that we can’t live without. Yet too much of certain types can have a negative impact on our health.

In this article we’ll discuss both the positives and negatives of dietary fat. Specifically, we’ll examine:

• What dietary fat is and what foods provide it.
• The role of fat.
• Fat and athletic performance.
• Fat, health, and weight loss.
• New Zealand’s pattern of fat intake.

And because nutrition in general is fundamental to human health; you can rest assured that we cover it in much greater detail in our Personal Trainer, Weight Management, and Professional Development courses.

What is dietary fat and what foods do we get it from?

Fats, also known as ‘Lipids’ are a major source of energy. In the Western world, they usually provide between 30-40% of Total Energy Intake (TEI).

Of the macronutrients, fat is by far the most ‘energy dense’. It provides 9 calories per gram as opposed to carbohydrate or protein which only provide 4.

You don’t have to consume a lot of fat for it to be a major energy source!

When referring to fats, its important to note that we’re also talking about ‘oils’ such as sunflower, olive and canola oil. The most obvious distinction is that fat tends to be solid at room temperature where oils are liquid. Chemically, they are very similar.

The building blocks of all fats are ‘fatty acids’. These are made up of the same three atoms as carbohydrate: carbon, hydrogen and oxygen. However, the arrangement and ratios of the atoms differ between fats and carbs.

In comparison to carbohydrate, fatty acids contain almost no oxygen. It’s the resulting higher proportion of carbon atoms and carbon-hydrogen (C-H) bonds that makes fat so energy dense. C-H bonds are simply more effective at storing potential chemical energy than other molecules.

Fats are divided into the following categories:

• Triglycerides.
• Sterols (such as Cholesterol).
• Phospholipids.

Triglycerides make up approximately 95% of the fat we consume and come from animal and plant foods.

As the name suggests, triglycerides are made up of one glycerol molecule linked to three (tri) fatty acid molecules. Once digested, triglycerides circulate around the bloodstream to be used as a source of energy. And when energy isn’t required for immediate use; triglycerides get stored in fat cells around the body.

It’s important to note that excess calories consumed from any macronutrient food source can be converted into, and stored as triglycerides.

The hips and belly are two major triglyceride storage areas.

Fatty acids are grouped according to their chemical characteristics. They can can either be:

• Saturated (SFA),
• Monounsaturated (MUFA), or
• Polyunsaturated (PUFA).

While most foods contain a combination of fatty acids, they’re classified according to what chemical characteristic predominates.

Saturated fats:

• Tend to be solid at room temperature.
• Come predominantly from animal sources: meat and dairy products.
• Have chains of carbon atoms that are ‘saturated’ by surrounding hydrogen atoms.

Unsaturated fats:

• Tend to be liquid at room temperature.
• Come predominantly from plant sources: vegetable oils, avocado, various nuts and seeds.
• Have fewer hydrogen atoms meaning their carbon atoms form double bonds with each other in the fatty acid chain.

Mono-(one) unsaturated fatty acids have a single carbon-to-carbon double bond. In comparison, poly-(many) unsaturated fatty acids have two or more double bonds in their carbon chain.

This difference in bonds is significant. Double bonds put a ‘kink’ or bend in the carbon chain, thus weakening the molecule. Weaker molecules struggle to hold a stable, solid form. This explains why unsaturated fats tend to be liquid at room temperature.

The position of the double bond on the carbon chain is also significant. You may have heard of ‘omega-3’ and ‘omega-6’ fatty acids. Increasingly, these fatty acids are being recognised for their beneficial effects, especially in protecting us from cardiovascular disease. The ‘3’ and ‘6’ of these fatty acids refers to the position of the first double bond on the carbon chain.

Food sources rich in these fatty acids include oily fish such as salmon (omega-3) and a variety of vegetable oils, nuts and seeds (omega-3 and omega-6).

What’s the role of fat?

As we’ve discussed, fat provides us with a major source of energy. This energy can be utilised for immediate use, or it can be stored and used as an energy reserve as required.

Less well known are some of the other roles that fats play. They:

• Provide insulation and cushioning: Visceral (of the internal organs) fat provide a protective layer that surrounds and protects many of our vital organs. Subcutaneous (under the skin) fat provides a layer of insulation that helps to regulate our body temperature.
• Enable the absorption of vitamins: Vitamins A, D, E, and K are known as the ‘fat-soluble vitamins’. This means that we can only absorb and utilise these essential vitamins with the help of fats.
• Provide structure: For example, fats help to form nerve cell membranes and insulate neurons. As such, they facilitate the signalling of electrical impulses throughout the nervous system allowing the body to ‘communicate’ with itself and the outside world.
• Produce and secrete hormones: For example, leptin is a hormone produced in and secreted by fat cells. Leptin informs the brain about the state of the bodies fat reserves. If the reserves are too low, energy demanding functions such as growth and reproduction are paused to save energy and preserve life.

Just like carbohydrates and protein, fat is an essential nutrient. For good all-round health, we need to consume it in relatively large quantities.

The question is – do we consume enough, too much, or too little? Are there any major problems with the typical kiwi’s fat intake?

What does New Zealand’s fat intake look like?

The Ministry of Health (MoH) Eating and Activity Guidelines recommends that adults consume the following quantities of fat-rich foods:

The ministry provides the following examples of what constitutes a daily serve:

• 1 cup (150g) cooked or canned beans, lentils, chickpeas, or split peas.
• 1 cup (250ml) low or reduced fat milk, buttermilk, or plant-based alternative (e.g., soy, rice, almond or oat milk).
• 170g of tofu, or 30g of nuts, seeds, peanut or almond butter.
• 2 large eggs.
• 2 slices of reduced fat cheese (e.g., Edam).
• 100g cooked fish fillet or one small can of fish.
• 80g cooked lean chicken or 65g cooked lean meat such as beef, lamb or pork.

Its worth noting that these serving sizes are often considerably smaller than what we’d expect. For example, if you ordered a steak at a restaurant, 250g would be considered standard. According to the ministry’s guidelines, this would constitute approximately 4 serves in one go!

Unfortunately, there’s an absence of data on New Zealand’s current fat intake. The ministry’s most recent Eating Guidelines reference the 2008/09 NZ Adult Nutrition Survey which found that:

• 50% usually use reduced or low-fat milk.
• 42% ate fresh or frozen fish at least once per week.
• 60% ate red meat at least three times per week.
• 29% ate nuts of which only 7% were whole nuts. 7% came from nut butters and 19% from hidden sources.

The ministry also notes that saturated fat contributes approximately 13% of our Total Energy Intake (TEI). This is higher than the recommended 10% which comes from a significant body of research showing a decreased risk of cardiovascular disease when:

• The intake of saturated fat is reduced and,
• Saturated fats are partially replaced with unsaturated fats, in particular polyunsaturated fats.

A scarier picture of our fat intake comes from the Helen Clark Foundation.

In 2018, the foundation collected EFTPOS data on fast-food spending across the Auckland region. A subsequent analysis of the data revealed that Aucklanders spend over $1 billion annually on fast-food. This is equivalent to:

• 89 Big Macs or
• 399 Wicked Wings or
• 560 slices of Pizza for every person in Auckland, every year!

Now, because:

• Fat is so energy dense, and
• New Zealand has a major problem with obesity and cardiovascular disease,

The MoH has produced a number of ‘eating statements‘ which recommend that people:

• Eat some milk and milk products – mostly low and reduced fat.
• Remove the visible fat from red meat.
• Choose and/or prepare foods and drinks with unsaturated instead of saturated fats.

Additionally, the MoH goes on to recommend that people exchange:

• Butter (predominantly saturated fat) for margarine or other plant-based spreads.
• Full-fat milk and cheese for low and reduced fat options.
• Coconut cream for coconut milk.
• High fat takeaways for healthier options (e.g., salad-rich kebabs, vegetable-rich non-fried Asian rice or noodle dishes).
• Highly processed high-fat convenience foods (snack bars and crisps) for whole or less processed foods (e.g., vegetables, fruit, unsalted nuts).

In terms of our general pattern of consumption, there is a consistent trend across all macronutrients.

This trend relates to quality and quantity in our food intake. Quite simply, we appear to be eating too much unhealthy (highly processed, fast and junk foods), and not enough healthy (fresh, unprocessed or lightly processed foods).

Debunking a popular myth – Is saturated fat really that bad?

As somewhat of a distraction, there appears to be an orchestrated attempt to ‘rehabilitate’ saturated fat. This is often associated with people advocating diets with a high meat intake (e.g., the Paleo diet).

The argument that is advanced often sounds something like:

“There is no conclusive scientific evidence that a high intake of saturated fat causes cardiovascular disease”.

While technically correct, this argument is also naïve and/or intentionally deceptive.

Let me explain…

Proving causality is the holy grail of scientific research. In this case, proving causality means showing that without doubt, a high saturated fat intake is guaranteed to cause cardiovascular disease.

Sounds straightforward right? Well, it’s not. Proving causality is anything but straightforward!

For example, a study designed to prove that a high saturated fat intake causes cardiovascular disease would need to:

• Control for (eliminate) the influence of factors such as a sedentary lifestyle and genetic predisposition (family history).
• Recruit a large sample of subjects without heart disease and make them follow a diet high in saturated fat for a prolonged period of time.
• Knowingly and intentionally create cardiovascular disease in a population of apparently healthy individuals.

Do you see the issue now?

A core principal of scientific research is that the research doesn’t harm human subjects. An ethics committee would never grant approval for research where there was a high probability that:

• Subjects would develop a disease resulting in reduced longevity or quality of life.

So, it’s unlikely that science will ever ‘prove’ a causal link between saturated fat and cardiovascular disease. This doesn’t negate the significant body of research that links high saturated fat intakes to cardiovascular disease. It also doesn’t negate the influence of other factors (e.g., sedentary lifestyles, smoking) to our leading cause of death.

Ultimately, fat is both essential for good health and problematic when consumed in excess.

Now does this hold true in a more athletic context?

Do the eating guidelines apply to athletes?

In our Personal Trainer programme we take a detailed look at the body’s three energy systems. Only one system, the aerobic (or ‘oxidative’) system utilises energy from fat. Oxygen is used by this system to help break down (oxidise) fatty acids to release their stored energy.

In comparison to the anaerobic energy systems, the chemical processes used to produce energy aerobically are particularly complex. This results in energy being produced slowly when it relies on fat oxidation.

Consequently, the aerobic energy system only fuels low-moderate intensity activities and recovery periods. Higher intensity activities require a rapid supply of energy.

Because we tend to have ‘ample’ stores of energy dense fat, many nutritional strategies have been employed to promote fatty acid oxidation. The rationale being – athletic performance will be enhanced by burning more fat and protecting the limited stores of carbohydrate.

These strategies have included low-carbohydrate high-fat (LCHF) diets and other fat-loading strategies.

Sports Nutritionists Burke and Hawley [ref 1] note that strategies oriented on increasing fat oxidation:

• Have been well investigated, and
• Show no clear evidence of any benefit to athletic performance.

Burke and Hawley note that chronic restriction of carbohydrate is more likely to impair athletic performance by:

• Interfering with the athletes ability to undertake high quality training, and
• Reducing the muscles ability to utilise its carbohydrate stores to support high-intensity events.

Sports Nutritionists O’Connor et al [ref 2] note that losing weight can be important for athletes to:

• Improve power-to-weight ratio.
• Attain a desired body composition.
• Make a pre-designated weight requirement for a competition.

According to O’Connor et al, for most athletes, reducing fat intake on its own is sufficient to produce any desired weight/fat loss.

Not only is this approach in-line with general eating guidelines, it’s less likely to result in glycogen (stored carbohydrate) depletion.

A Final Word

Clearly, fat is an essential macronutrient with many vital functions. However, due to its energy density, it’s easy to over-consume and thus add to our expanding girths.

In a study of the food industry, Michael Moss [ref 3] reveals that fat is added in large quantities to many foods. The reason being – fat has an extremely pleasant ‘mouthfeel’. Think about how roast meat, pork crackling, and full fat ice-cream/yogurt ‘feel’, taste, and then slide down the throat.

Fatty foods are a guaranteed feel-good event and emotional pick-me up. The consumption of fatty foods encourages further consumption, a habit-forming issue which we address in our Weight Management programme.

It’s likely that the saturated fat debate will continue. Maybe saturated fat isn’t the specific danger to our health past research has suggested. Maybe it is. In many regards this debate is irrelevant. Because without doubt, obesity, as a marker of an excess energy intake, is a major risk to our health.

So, because fat in general is so energy dense, it makes sense to reduce our intake of it.

In this regard, it’s hard to argue against the MoH guidelines and ‘exchange’ recommendations!

References

1. Burke and Hawley. (2017). Nutritional strategies to enhance fat oxidation during aerobic exercise. In Burke and Deakin. Clinical Sports Nutrition (5th Ed). Australia: McGraw Hill Education.
2. O’Connor, Honey, and Caterson. (2017). Weight loss and the athlete. In Burke and Deakin. Clinical Sports Nutrition (5th Ed). Australia: McGraw Hill Education.
3. Moss. (2013). Salt, Sugar, Fat: How the Food Giants Hooked Us (1st Ed). Random House.