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6 Risks of Eating a Low-Fat Diet

How Low Can You Go? The Big Fat Truth about Low-Fat Diets

-- By Sarah Haan, Registered Dietitian

The all-or-nothing mentality prevails in our society. Here at SparkPeople though, we know better. Moderation is our mantra, and we repeat it so often that most of us understand the importance of applying it to exercise, eating and setting goals. Still, there's one thing that many of us fear so much that we forgo moderation and head to extremes: fat. The residual effects of the low-fat craze of the 1990s linger, causing many people to believe that less is more when it comes to fat. 

Being conscious of your dietary fat intake is definitely a good thing, especially when you're trying to reduce your risk of heart disease or lose weight. But if you take it too far, you could be putting your health in jeopardy.

So how much fat do you need?
For healthy adults, the Dietary Guidelines for Americans recommend 20% to 35% of your daily calories come from fat. Both SparkPeople and the American Heart Association take a middle of the road approach, advocating a 30% fat intake. Use the following chart (or refer to your SparkDiet plan) to see your estimated daily fat recommendations based on these ranges.

Recommended Daily Fat Intake Based on Calorie Needs
 
Daily Calories Ideal Fat Intake* Too Low^ Too High+
1,200 27-47 g < 27 g > 47 g
1,300 28-51 g < 28 g > 51 g
1,400 31-54 g < 31 g > 54 g
1,500 33-58 g < 33 g > 58 g
1,600 36-62 g < 36 g > 62 g
1,700 38-66 g < 38 g > 66 g
1,800 40-70 g < 40 g > 70 g
1,900 42-74 g < 42 g > 74 g
2,000 44-78 g < 44 g > 78 g
2,100 47-82 g < 47 g > 82 g
2,200 49-86 g < 49 g > 86 g
2,300 51-89 g < 51 g > 89 g
2,400 53-93 g < 53 g > 93 g

*20%-35% of daily calories
^Less than 20% of daily calories
+Greater than 35% of daily calories

Lower fat isn't necessarily better. Regularly consuming fewer than 20% of your daily calories from fat (see "Too Low" on the chart above) will put your health at risk in many ways as discussed above. A diet too high in fat (see "Too High" on the chart above) can also lead to problems—heart disease, diabetes, cancer and weight gain. Here are six health risks you're taking when you restrict your fat intake too far.

1. Poor Vitamin Absorption
Eating a diet too low in fat can interfere with the absorption of the fat-soluble vitamins A, D, E and K. Because these nutrients are fat soluble, your body needs dietary fat to utilize them. These vitamins are stored mostly in the liver and fat tissue and are important in bodily functions such as growth, immunity, cell repair and blood clotting. If you're not eating enough fat to bring these vitamins into your body, they will be excreted, and you may be at risk for a vitamin deficiency.

2. Depression
A diet that's too low in fat—especially essential fatty acids, which your body can only get from food—might hurt your mental health. Both omega-3s and omega-6s play roles in mood and behavior. They are the precursor to many hormones and chemicals produced in the brain. One study published in the Journal of Affective Disorders has linked low and abnormal essential fatty acid intake to depressive symptoms. Other research shows that, because fatty acids help to insulate nerve cells in the brain, allowing these nerve cells to better communicate with one another. People who are deficient in omega-3s may suffer from bipolar disorder, schizophrenia, eating disorders, and ADHD. <pagebreak>

3. Increased Cancer Risk
Colon, breast, and prostate cancers have all been correlated with low intakes of essential fatty acids. Research has shown that a high intake of omega-3s slows prostate tumor and cancer cell growth, too. If your diet lacks healthy fats, you could be increasing your risk of cancer.

4. High Cholesterol and Heart Disease
Low-fat diets also play a role in cholesterol levels and heart disease. When your diet is too low in fat, your body's level of HDL (the "good" cholesterol) goes down. This is problematic because you want your HDL level to be high to help protect against heart disease. HDL collects "bad" cholesterol from the blood and transports it to the liver for excretion. When those ratios are out of balance—and when your LDL ("bad" cholesterol) level gets too high, you face cholesterol problems and an increased risk of heart disease. Essential fatty acids, especially Omega-3s, can elevate HDL, improve cholesterol levels and protect the heart.

5. Imbalance of Nutrients—Especially Carbs
If you're not eating enough fat, then you're likely getting too much of other things, namely carbs and/or protein. This affects the overall balance of your diet, which could lead to health problems. A carbohydrate-rich diet can inflate appetite and girth and increases your chances of developing type 2 diabetes. On the flip side, a high-protein diet taxes the kidneys and liver and can lead to osteoporosis. Both cases can result in nutrient deficiencies. The key is to balance all three macronutrients—fat, carbs and protein—to ensure optimal nutrition and disease prevention (more on that below).

6. Overeating
If you're always choosing low-fat or fat-free foods at the grocery store, you could be shortchanging your weight-loss efforts. Many of these processed foods contain added sugars to enhance taste; often they're similar in calories to the original full-fat product. Research has shown that people tend to believe these foods are "freebies" and will even overeat them, thinking they're healthy or low in calories when they're anything but. Plus, fat helps carry flavor in our foods. It leads to fullness and satiety, which means you can get by longer on a meal or snack that provides fat without feeling the need to eat again soon. When that fat is missing, your appetite may get the best of you.


Considering the health risks of not eating enough fat, it is definitely important to include enough in your diet daily. However, not all fats are created equal. Foods such as avocados, canola and olive oil, almonds, tuna, salmon and flaxseed are all excellent sources of healthy fats. High-fat meats and dairy products, trans fats (hydrogenated oils), and saturated fats should be limited. To learn more about the best and worst fats for your diet, refer to the following SparkPeople articles:
Fats that Fight Cholesterol
The Mega Benefits of Omega-3s
Reference Guide for Fats
Translating Those Trans Fats
Just as eating too few calories can hurt your weight-loss efforts, a diet too low in fat can hurt your health, too. Enjoy a moderate amount of fat daily with the peace of mind that you are protecting your heart, brain and your body with every bite.

Selected Sources
Maes, Michael, et al. 26 April 1996. Fatty acid composition in major depression: decreased ω3 fractions in cholesteryl esters and increased C20:4ω6/C20:5ω3 ratio in cholesteryl esters and phospholipids . Journal of Affective Disorders. 38 (1): 35-46.

Fat 101. The American Heart Association. Fat. The American Heart Association (accessed September 15, 2009).

This article has been reviewed and approved by SparkPeople nutrition experts, Becky Hand, Licensed and Registered Dietitian, and Tanya Jolliffe, healthy eating expert.
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