Heart Niagara is pleased to announce our guest blogger, Dr. Amber Merrick BSc, N.D.
Below, she shares her thoughts on “Low Fat Diets” and their myths.
For years we have been told to consume low fat diets to maintain a healthy weight, and decrease our risks of many chronic diseases like cardiovascular disease (CVD). This nutrition myth was based on flimsy evidence, and we now know that fat is an incredibly important part of a heart healthy diet (1).
Why were we told fat is bad?
The theory is as follows:
- Saturated fat raises LDL (“bad”) cholesterol in the blood.
- LDL cholesterol lodges in the arteries, causing atherosclerosis and eventually, heart disease.
This theory has never been proven, despite it having been the cornerstone of dietary recommendations since 1977. In fact, NO research exists correlating intake of dietary fats, including saturated fats, with risk of coronary heart disease, stroke, or CVD (2).
Why fat is actually beneficial for our health!
Fat has many roles in the human body:
- Protection: insulation to regulate body temperature and cushioning to protect body organs
- Promotes growth and development, as well as maintaining cell membranes
- Digestion of vitamins A, D, E, and K (fat soluble)
Problems with a low fat diet.
Low fat foods tend to leave us hungry and unsatisfied, and we will likely eat more sugar and carbohydrates to compensate. This leaves our blood sugar prone to highs and lows, with subsequent carbohydrate and sugar cravings. Fats slow the release of sugar into the blood stream and provide us with high levels of nutrients and healthy calories.
HDL is known as the “good” cholesterol and is associated with a reduced risk of heart disease. Studies show that a low-fat diet reduces blood levels of HDL (3).
Elevated LDL levels are associated with an increased risk of cardiovascular disease; however, new data is showing that there are subtypes of LDL. We have small, dense LDL and Large LDL. The small, dense LDL (sdLDL) contribute to heart disease, NOT the large ones (4, 5). A high intake of carbohydrates (especially refined carbohydrates and sugar) increases sdLDL, while dietary saturated fat and cholesterol change the particles from the small, dense (bad) LDL to the large (benign) LDL (6, 7, 8).
Testosterone is the main sex hormone in males, but it is important for women too. One of the side effects of a low-fat diet is significantly reduced testosterone levels (9). Having low testosterone levels can lead to decreased muscle mass, increased body fat, osteoporosis, depression, and decreased libido, among others.
But not all fats are created equal…
Of course, there are some bad fats in the diet that actually DO raise the risk of heart disease.
- Trans fats are unsaturated fats that have been put through a hydrogenation process, which increases their shelf life and makes them resemble saturated fats in consistency. Trans fats, found mainly in processed foods, are strongly associated with an increased risk of heart disease.
- Vegetable oils like soybean and corn oil that are very high in Omega-6 fatty acids are also strongly associated with heart disease risk and inflammation.
So what should you eat?
One of the best diets to decrease risk of cardiovascular disease, obesity and Type 2 diabetes is the Mediterranean diet (10, 11). This diet is very high in colorful vegetables, and fruit, some high fiber whole grains (I recommend no more than 3 servings per day), fish, meats, eggs, legumes, dairy, nuts and seeds. It is quite low in sugary, processed foods, although it does incorporate the occasional glass of red wine. It also promotes regular physical activity, and a pleasant, social eating environment.
As for fats, I generally recommend women consume approximately 1-2 thumb size servings of fat per meal and men 2-4 per meal. You should choose heart healthy saturated and monounsaturated fats and oils like avocado, coconut oil, olive oil, almonds and walnuts. Eat some Omega-3s from fish and grass-fed animals, but stay away from trans fats and vegetable oils.
Amber Merrick is a licensed and registered Naturopathic Doctor in the province of Ontario. She began her learning career at Brock University in St. Catharines, Ontario where she graduated with honours and earned a Bachelor of Science degree in Neurobiology. After graduation, she worked in the mental health field as a behavioural therapist assistant and case manager supporting individuals with mental health concerns in the justice system.