2. Fish contains large amounts of healthy fats
It's absolutely no surprise that of all the sources of calories and carbohydrates, protein and dietary fat and the one that is most "fattening" is dietary fat. That's because fat is more efficiently stored as bodyfat than carbs or protein. But there's an exception: healthy fats, such as those found in fish. The healthy fats in fish and the omega-3 fatty acids are less likely to be stored as bodyfat than the fats from sources such as chicken legs, beef, egg yolks or vegetable oil. The fat consumed from fish is prioritized for important physiological processes and only after those jobs have been completed does it tend to exert an effect on bodyfat storage. These jobs include sparing the breakdown and burning of glutamine, the all-important amino acid that prevents muscle loss; supporting the production of growth hormone; and increasing the formation of muscle glycogen.
With respect to glycogen, fish fat helps funnel carbs into muscles, which not only contributes to muscle growth but also compromises the body's ability to create bodyfat from carbohydrates. How so? When glycogen storage increases, the body's ability to make bodyfat from carbohydrates correspondingly decreases. One dieting secret is that the leaner you get, the more difficult it becomes to store fat from fish as bodyfat.
A precontest bodybuilder who has done his homework can get away with eating a lot of fish high in fat with little worry of adding bodyfat. This fat also prevents muscle breakdown and can enhance muscle growth.
GO FISH: For the omega-3 content of several types of seafood, see the "Omega Man" sidebar.
3. Fish is high in mineral content
Most types of fish are a good source of both selenium and iodine, minerals that support metabolic rate. Iodine feeds the thyroid, the "master" gland that has a huge impact on calorie burning and metabolism. Adequate amounts of iodine help keep that gland healthy. A strong thyroid gland also contributes to a stronger immune system, which is particularly important during dieting and hard-training phases.
Some research has been critical of selenium as a thyroid supporter, but the truth is that it contributes to thyroid function and may even increase thyroid levels. The real problem is in taking boatloads of selenium supplements that can backfire, actually reversing the speed of the metabolism. Getting adequate amounts, ideally 100- 400 micrograms a day can have a positive effect. (Three ounces of raw oysters have a little more than 60 micrograms.) Fish also supplies chromium, a trace mineral that helps in the utilization of carbohydrates. A prevailing theory holds that chromium makes growth receptors on muscle tissue more "sensitive" resulting in greater glycogen storage and enhanced amino-acid uptake. Oysters are not only dense in chromium, but also high in zinc, another vital mineral that supports testosterone production. Although other protein foods contain zinc, there's no better source than oysters. Sardines are high in calcium and omega-3s. Some experts speculate that high calcium intake can make the body less efficient at manufacturing bodyfat. Calcium helps alter calcitriol levels, making the body a poor fat storer, and omegas shift fuel sources in the body, coaxing it to burn fat as energy rather than rely on carbohydrates for energy.
GO FISH: To increase the range of minerals you take in, consume a variety of seafood. For iodine, emphasize oysters, cod, sea bass, haddock and perch. To boost calcium, consume bone-in fish, such as sardines.