A lot of people believe you can lose weight by eating fish. At least as many people, if not more, have heard there may be a connection between eating fish and weight loss and are curious if it’s true.

However, the relationship between fish diets and weight loss is not as simple as it may seem. A good weight loss diet needs to be low in calories and high in nutrients.

Fish can be a great addition to a good weight loss diet. It’s an equally good addition to a high-protein diet designed to support muscle growth. There are plenty of arguments for eating more fish but it’s important to focus on your diet as a whole instead of only putting extra focus on fish.

A good way to do this is to start eating a Mediterranean diet. The Mediterranean diet is one of the healthiest diets in the world and it places a strong emphasis on fish and vegetables.

Fish can also be a good food option for the Keto Diet. However, despite its popularity, the Keto Diet presents several risks and has been ranked one of the worst diets in the world. (https://globalnews.ca/news/6376259/keto-diet-dangerous/)

I’m a big fan of the Mediterranean Diet but I would never abuse my body by forcing it into ketosis.

Plenty of people have lost weight by eating a Mediterranean diet that has plenty of fish and vegetables. This isn’t just because they were eating more of these healthy foods though. It’s also due to the fact they used them to replace unhealthier options that are high in sugar and saturated fats.

But that’s enough about the Mediterranean diet for now. You’re here because you are curious about the weight loss value of fish. If you want to know more about eating the Mediterranean way, I have an article about it elsewhere on this site.


​4 Reasons Why Fish Is a Good Diet Food Choice

Fish can support your weight loss efforts in several ways. Let’s take at each of them one by one.


1. Fish Is Good for Filling Your Stomach

Fish is high in protein. Like fiber, protein takes time to digest so it loiters in your stomach for a while helping make it feel full.

Of course, other food choices, including vegan-friendly options like lentils and beans, are high in protein too. However fish has certain advantages (appetite-wise) over them.

Most fish is very low in fat and, unlike vegan proteins, it does not provide any carbs at all.

The relationship between protein intake and appetite is well known. It has been evaluated and proved in many scientific studies.

If you are interested in learning more about the ways a high-protein diet can prevent and treat obesity, this research paper published in Missouri Medicine will make interesting reading: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6179508/

Plenty of research suggests fish proteins are more filling than animal proteins and, although the difference in appetite may only be slight, the participants who at fish in one study still consumed significantly fewer calories during their following meal than the participants who had been eating beef. (https://pubmed.ncbi.nlm.nih.gov/16482079/)

If you tweak your diet so that it contains more fish protein and less starchy carbohydrates, such as potatoes, rice, and pasta it will help your stomach feel fuller for longer.


​2. Eating Fish Reduces Your Fat Intake

Fish contains significantly less fat than animal proteins like beef, pork, and lamb. Fat provides nine calories per gram. That fact alone explains why you may be able to lose extra weight by eating fish. Though, once again, I must point out the need to take a sensible approach to weight loss and limit the amount of calories you consume in a day.

Oily fish, such as salmon and mackerel, could be seen as being poorer options than white fish such as haddock and hake, but this is not the case. Unlike meats that provide saturated fats, fish oils contain health-boosting fats like Omega-3.

Omega-3 is associated with many health benefits and is known to support heart health. According to Hearth Health UK, eating foods that are high in Omega-3 may help prevent heart attacks and strokes. (https://www.heartuk.org.uk/low-cholesterol-foods/omega-3-fats)


​3. The Omega-3 Fatty Acids in Some Fish May Offer Weight Loss Benefits of their Own

But how do Omega-3 fatty acids support weight loss? As with most of the best diet pills, they appear to do it by suppressing appetite and boosting metabolism.


​Appetite Suppression

At this point, I must point out the appetite suppressing ability of Omega-3 is separate from the hunger-suppressing ability of fish protein. Researchers exploring the connection between appetite and omega-3s generally use omega-3 fish oil supplements, not servings of oily fish.

The researchers in charge of one study gave some of the volunteers 0.3 mg of fish oil per day and 1.3 mg of omega-3 fish oil to the rest. The people who got the high dose reported feeling significantly fuller for up to two hours after eating their meal. (https://pubmed.ncbi.nlm.nih.gov/18602429/)

However, some studies show conflicting results. The results of one study suggest Omega-3 fish oils may actually cause some people to experience an increase in hunger so it appears the oils may work differently on an individual level. (https://pubmed.ncbi.nlm.nih.gov/23474089/)


​Faster Metabolism

The speed of your metabolism influences the number of calories you burn per day. A faster metabolism burns more calories. A slower one burns less.

The results of a study conducted in France show six grams of fish oil per day, taken for 12 weeks, increased the metabolism of the volunteers by 3.8 percent. (https://pubmed.ncbi.nlm.nih.gov/15481762/)

In another 12-week study, this time involving only women, a dose of three grams of fish oil per day boosted the women’s metabolisms by around 14 percent and energy expenditure during exercise increased by 10 percent.

Data from the same study also shows the fish oil supplements increased fat oxidization by 27 percent during exercise and 19 percent while resting. (https://pubmed.ncbi.nlm.nih.gov/26679702/)

However, this is an article about how eating fish can help you to lose weight, not the things omega-3 can do. Many fish don’t provide omega-3, so it’s time to move on.


​4. Fish Is Low in Calories

In addition to being high in protein, fish is also low in calories. Unless you have a fish allergy, it can be an excellent substitute for meat.

Of course, how you cook your fish can make a difference. Frying it will add extra calories. Grilling or poaching your fish are healthier options.


​Is Eating a Fish Diet a Good Idea?

There are arguments for and against eating fish every day as your main source of protein, but plenty of people do it.

The pescatarian diet bridges the gap between meat-eating and veganism by avoiding meats and choosing fish instead.

However, as an article published on Medical News Today points out, some fish choices contain high levels of mercury so eating them all the time would be unwise. (https://www.medicalnewstoday.com/articles/323907)

The US Food and Drug Administration (FDA) provides a list of best and worst fish choices. I’ve provided a screenshot below. You can find the page I took it from here: https://www.fda.gov/media/102331/download

The FDA's List of Best and Worst Fish Choices


As you can see, if you stick to the “best choices”, the FDA suggests eating two to three servings of fish per week.

However, pescatarians and people following the Mediterranean diet often eat more and appear to boast superior levels of good health.

I often eat more than three portions of fish per week but all the fish I eat is a good match for the FDA’s best options.

Like a lot of people, I also try to eat oily fish, such as salmon or mackerel, twice per week. Apart from providing Omega-3, these oilier fish options are good for providing Vitamin D.

Vitamin D is a fat-soluble vitamin that supports healthy immune function and aids testosterone production. It’s important. Your body needs it but Vitamin D deficiency is surprisingly common.

However, in line with NHS guidelines, I never eat more than two portions of fatty fish per week.

Final Thoughts

Too many people become obsessed with certain types of diet. The Keto Diet is a good example but that’s not surprising because it gets such a lot of media coverage.

Others decide to go “high-protein”, “low-carb”, or do any of the many variations of intermittent fasting. There are enough fad diets to boggle the mind. Some have virtues but many do not. Losing weight is a destination. There are many ways you can make the journey and some of them can give you a pretty dangerous ride.

Eating more fish instead of meat can be a good way to lose weight faster. Especially if you are using fresh fish as a substitute for processed meats such as sausages, burgers, and tins of chopped pork and ham, etc.

However, regardless of whether you want to lose weight, build muscle, or maintain excellent good health; your body needs more than fish to do it.

Fruit and vegetables provide important vitamins, minerals, and dietary fiber. You need these nutrients too, and the antioxidants fruit and vegetables provide also support your immune system and help prevent early aging of the skin.

There are strong arguments for adding more fish to your diet, but it’s a good idea to focus on your overall diet. As I mentioned earlier in this article, the Mediterranean diet is one of the healthiest diets in the world. It’s a great option for anyone who plans to eat more fish and/or lose weight.

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