Can Omega-3s Help You Lose Weight?

by Marixie Ann Obsioma, MT, undergrad MD on February 17, 2021
Last updated on May 23, 2021

When it comes to fat, there’s one type you surely don’t want to cut back on and that is omega-3 fatty acids. They are present in many foods and dietary supplements. 

Can Omega-3s Help You Lose Weight

According to a comprehensive survey on the use of complementary health approaches in the US, omega-3 supplements have become one of the most popular natural products being consumed by both adults and children. The survey findings indicated that about 18.8 million and 664,000 children age 4 to 17 are taking fish oil supplements (1).

Beyond the basic maintenance of cells in our body, studies have linked omega-3 fatty acids with various other health benefits. Keep reading to discover what omega-3 fatty acid is, how can it make a difference for you, what is the recommended dosage, and are there any risks involved? 

What Is Omega 3-Fatty Acid? 

When we talk about the power of omega-3 fatty acids, the entire omega-3 family tends to get lumped into the same category. Unfortunately, not all omega-3 molecules function similarly, and some are more effective than others.

The term “omega-3” is actually an old-fashioned classification referring to a whole family of omega-3 fatty acids. There are several types of omega-3 fats, but the most important ones can be categorized into two main groups:

  • Essential Omega-3 Fatty Acids: Alpha-linolenic acid (ALA) is the only essential omega-3 fatty acid. It is found in a wide range of plant foods. Walnuts, hemp seeds, chia seeds, flaxseeds and their oils are the richest sources.
  • Long-Chain Omega-3 Fatty Acids: The main workhorses of the omega-3 fatty acid family are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). They are mainly found in fish oil and fatty fish, but also in seafood, algae and algae oil. These two long-chain fatty acids promote the exchange of nutrients across the cell membrane and control the body’s inflammatory response.

For the last 4 decades, experts have extensively researched the effects of EPA and DHA on everything from lowering cholesterol and blood pressure to positively impacting weight loss, mood disorders, cancers, joint problems, and dry eyes. Newer studies are also looking at how these fatty acids influence our gut bacteria.

How Do Omega-3s Work for Lose Weight? 

Omega-3 fatty acid can help you lose weight in several ways: 

1. It Reduces Hunger and Appetite 

Fish oil may be most effective at reducing hunger and appetite in healthy people following a weight loss diet. Evidence showed that healthy people on a weight loss diet who consumed more than 1.3 grams of fish oil omega-3s daily felt fuller up to 2 hours after a meal (2). 

However, these effects are not universal. One study observed that fish oil omega-3s increased the levels of a fullness hormone in obese people, but decreased levels of the same hormone in non-obese people (3). Thus, it is possible that effects vary depending on your health status and diet. However, more studies are needed before strong conclusions can be made.

2. It Boosts Metabolism 

Another way omega-3 fatty acids may help you lose weight is by increasing your metabolism. Your metabolism can be measured by your metabolic rate, which determines the number of calories you burn each day. The higher your metabolic rate, the more calories you burn and the easier it is to lose weight and keep it off.

Evidence revealed that healthy young adults who took 6 grams of fish oil daily for 12 weeks experienced an increase of approximately 3.8% in their metabolic rates (4).

In another study, healthy older women who took 3 grams of fish oil daily for 12 weeks, had their metabolic rates increased by around 14%, which is the same as burning an extra 187 calories per day (5).

More recently, evidence found that healthy adults who consumed 3 grams of fish oil per day for 12 weeks, had their metabolic rate increased by more than 5% (6).

Most of the studies reporting increases in metabolic rates also observed an increase in muscle mass. Muscle burns more calories than fat, thus an increase in muscle mass may explain the higher metabolic rates observed in these studies.

But then again, not all studies have observed this effect. Thus, more studies are needed to understand the exact effects of omega-3s on metabolic rates (7).

3. It Enhances the Effects of Physical Activity 

The metabolic effects of omega-3 fatty acids may not be limited to simply increasing how many calories you burn each day. Studies suggest that consuming fish oil may also amplify the number of calories and amount of fat you burn during exercise.

Experts believe this happens because omega-3s may help you switch from using carbohydrates to fat as a source of fuel during exercise. Women who were given 3 grams of fish oil daily for 12 weeks burned 10% more calories and 19–27% more fats after exercise (8). This finding may explain why some studies have found that combining fish oil supplements and exercise is more effective at reducing body fat than exercise alone (9).

4. It Helps You Lose Fat and Inches

Though omega-3s don’t help some people lose weight, they may still help them build muscle and lose body fat.

Sometimes your weight on the scale can be misleading. It may remain the same even if you’re gaining muscle and losing fat. That’s why people who want to lose weight are often encouraged to use a tape measure or track their body fat percentages to assess their progress, rather than rely only on the scale.

For example, a study involving more than 40 people reported that those who were given 4 grams of fish oil daily failed to lose more weight as compared to those who got a placebo. However, it is the fish oil group who lost 1.1 more pounds of body fat and built 1.1 more pounds of muscle than those who were not given the supplement (10).

Another evidence showed that healthy adults who replaced 6 grams of fat in their diets with 6 grams of fish oil daily for 3 weeks did not experience any change in weight, but they did lose more body fat (4).

Similarly, another small study observed that people who consumed 3 grams of fish oil per day lost 1.3 more pounds of fat than those given a placebo. However, their total body weights remained unchanged (11).

Accordingly, a review of 21 studies concluded that omega-3s don’t reduce body weight more effectively than a placebo. However, the review showed that they can reduce waist circumference and waist-to-hip ratio more effectively (12). 

Thus, fish oil may not help you lose weight per se, but it may make it easier for you to lose inches and help you go down in clothing sizes.

Other Health Benefits 

Aside from weight loss, omega-3s can offer a slew of other health benefits: 

1. It Fights Depression and Anxiety 

For sure, you have heard about depression. It is one of the most common mental illnesses in the world. Patients commonly suffer from sadness, lethargy and a general loss of interest in life. Anxiety, on the other hand, is also very common and is characterized by constant worry and nervousness. 

Interestingly, studies indicate that people who take omega-3s regularly are less likely to be depressed (13, 14). Also, patients with depression and anxiety improved their symptoms after taking omega-3 supplements (15, 16, 17). 

Of the three types of omega-3 fatty acid, EPA appears to be the best at fighting depression (18). One study even found EPA as potent against depression as a common antidepressant drug (19).

2. It Improves Eye Health

DHA, a type of omega-3, is a major structural component of the retina (20). If you lack DHA, vision problems may occur (21, 22). 

Interestingly, consuming enough omega-3 is linked to a decreased risk of macular degeneration, which is the world’s leading causes of permanent eye damage and blindness (23, 24). 

3. It Promotes Brain Health During Pregnancy and Early in Life 

Omega-3s are very important for brain growth and development in infants. DHA accounts for 40% of polyunsaturated fatty acids in your brain and 60% in the retina of your eye (22, 25). Therefore, it’s not surprising to know that infants fed a DHA-fortified formula have better eyesight (26).

Getting enough omega-3s during pregnancy is associated with numerous benefits for your child, including (27, 28, 29):

  • Higher intelligence
  • Better communication and social skills
  • Fewer behavioral problems
  • Decreased risk of developmental delay
  • Decreased risk of ADHD, autism and cerebral palsy

4. It Decreases Risk Factors for Heart Disease

Who doesn’t fear heart attacks and strokes? We know them as today’s leading causes of death. Years back, experts observed that fish-eating communities had fewer cases of these diseases. This was later linked to omega-3 fatty acid consumption (30, 31). Since then, omega-3s have been tied to several benefits for the heart. Omega-3s can:

  • Cause a major reduction in triglycerides, usually in the range of 15–30% (32, 33).
  • Reduce blood pressure levels in people with high blood pressure (32, 34). 
  • Increases HDL “good” cholesterol levels (35, 36). 
  • Can keep blood platelets from clumping together, thus preventing blood clots (37, 38). 
  • Keeps your arteries smooth and damage-free to help prevent plaques from hardening (39, 40). 
  • Reduce the production of substances released during inflammatory response (41, 42). 

5. It Reduces Symptoms of ADHD in Children

Attention deficit hyperactivity disorder (ADHD) is a behavioral disorder characterized by inattention, hyperactivity and impulsivity. Several studies have noted that kids with ADHD have lower blood levels of omega-3 fatty acids (43, 44).

What’s more is that several pieces of evidence observed that omega-3 supplements can reduce the symptoms of ADHD.

Omega-3s help improve inattention and task completion. They can also help decrease hyperactivity, impulsiveness, restlessness and aggression (45, 46, 47, 48).

Recently, experts noticed that that omega-3 supplements were one of the most promising treatments for ADHD (49).

6. It Lessens Symptoms of Metabolic Syndrome 

Metabolic syndrome is a collection of conditions. It often includes central obesity — also known as belly fat — as well as high blood pressure, insulin resistance, high triglycerides and low “good” HDL cholesterol levels.

Omega-3 fatty acids can help improve insulin resistance, inflammation and heart disease risk factors in people with metabolic syndrome (50, 51, 52).

7. It Battles Autoimmune Diseases

In autoimmune diseases, your immune system mistakes healthy cells for foreign cells and starts attacking them.

Studies show that getting enough omega-3s during your first year of life is linked to a reduced risk of many autoimmune diseases, including type 1 diabetes, autoimmune diabetes and multiple sclerosis (53, 54, 55).

Omega-3s can also help treat lupus, rheumatoid arthritis, ulcerative colitis, Crohn’s disease and psoriasis (56, 57, 58, 59).

8. It Mends Mental Disorders

Low omega-3 levels have been reported in people with psychiatric disorders. Pieces of evidence suggest that omega-3 supplements can reduce the frequency of mood swings and relapses in people with both schizophrenia and bipolar disorder (60, 61, 62). Supplementing with omega-3 fatty acids may also decrease violent behavior (63).

9. It Prevents Age-Related Mental Decline and Alzheimer’s Disease

A decline in brain function is one of the unavoidable consequences of aging. Several studies link higher omega-3 intake to decreased age-related mental decline and a reduced risk of Alzheimer’s disease (64, 65).

10. It Protects Against Cancer 

Cancer is one of the leading causes of death in the Western world, and omega-3 fatty acids have long been claimed to reduce the risk of certain cancers. Interestingly, studies show that people who consume the most omega-3s have up to a 55% lower risk of colon cancer (66, 67).

Additionally, omega-3 consumption is linked to a reduced risk of prostate cancer in men and breast cancer in women. However, not all studies give the same results (68, 69, 70).

11. It Guards Kids from Asthma 

Asthma, a chronic lung disease, often presents with symptoms such as coughing, wheezing, and shortness of breath. Severe attacks are dangerous. They are caused by swelling in the airways. 

Many studies link omega-3 consumption with a decreased risk of asthma in kids and young adults (71, 72). 

12. It Removes Fat in Your Liver 

Non-alcoholic fatty liver disease (NAFLD) is more common than you think. It has increased with the obesity epidemic to become the most common cause of chronic liver disease in the Western world. 

The good news is, regular consumption or supplementation with omega-3 fatty acids can effectively reduce liver fat and inflammation in patients with NAFLD (73).

13. It Makes You Sleep Better

Good sleep is one of the foundations of optimal health. Studies tie sleep deprivation to many diseases, including obesity, diabetes and depression.

Low levels of omega-3 fatty acids are associated with sleep problems in children and obstructive sleep apnea in adults (74, 75).

Low levels of DHA are also linked to lower levels of the hormone melatonin, which helps you fall asleep (76).

Studies in both children and adults reveal that supplementing with omega-3 increases the length and quality of sleep.

14. It Is Good for Your Skin

DHA is a structural component of your skin. It is responsible for the health of cell membranes, which make up a large part of your skin. A healthy cell membrane results in soft, moist, supple and wrinkle-free skin.

EPA also benefits your skin in several ways, such as (77): 

  • Managing oil production and hydration of your skin
  • Preventing hyper-keratinization of hair follicles, which appears as the little red bumps often seen on upper arms
  • Reducing premature aging of your skin
  • Reducing the risk of acne.

Omega-3s can also protect your skin from sun damage. EPA helps block the release of substances that eat away at the collagen in your skin after sun exposure (78).

How Can You Get Enough EPA and DHA?

EPA and DHA are found almost exclusively in fresh fish and fish oil. Certain plants sources such as walnuts and chia seeds contain a shorter-chained omega-3 fatty acid called ALA. While our body has enzymes that convert ALA into EPA, and to some extent DHA, this conversion rate is so low that most experts consider it inconsequential (79). This is why the strength of an omega-3 supplement is typically measured by the amount of EPA and DHA alone.

How Much Should You Eat? 

If you do not eat 1–2 portions of oily fish per week, you may want to consider taking a fish oil supplement.

EPA and DHA dosage recommendations vary depending on your age and health.

The WHO recommends a daily intake of 200–500 mg of combined EPA and DHA. However, it may be necessary to increase the dosage if you are pregnant, nursing, or at risk of heart disease (80). Choose a fish oil supplement that provides at least 300 mg of EPA and DHA per serving.

If you want to lose weight, most recent studies used daily dosages of 300-3000 mg. Intake of omega-3s is generally safe as long as your daily dose does not go beyond 3000 mg (81). 

Key Takeaway

Omega-3 fatty acids are an important part of your nutrition and contribute to the basic health of all cells in the body. You can get enough omega-3 fatty acids in your diet to enjoy most of its benefits.

While there are clear evidence that consuming omega-3s can help reduce your chance of developing cardiovascular illnesses, Studies supporting its other health benefits appear to be modest, and they may not apply to everyone.

Overall, omega-3s are likely to have the most beneficial effects when combined with lifestyle factors like proper nutrition and regular physical activity.


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