The best high-protein slimming diet contains lots of taurine and glycine
If you're looking to lose a couple of pounds of fat, a high-protein diet is often the best option. But what's the best kind of protein for weight loss? According to Scandinavian researchers, the best slimming proteins are found in shellfish. These contain relatively large amounts of taurine and glycine.
The researchers performed experiments with five groups of mice. Four groups were fed a diet for six weeks that would make them fatter: it contained lots of sugar and fat. A control group was given a high-sugar low-fat diet.
The protein in the low-fat diet was casein; in the four experimental groups the protein was chicken, cod, crab or scallop. The scallop was the shellfish, or the researchers used Canadian scallop, aka Placopecten magellanicus.
The researchers wanted to know what effect the different proteins had on obesity. There are indications that some proteins are better at reducing excess fat deposition than others. For example, a 2009 study suggests that it's easier to lose weight by making lean fish your main source of protein rather than lean meat.
The proteins in fish contain large amounts of taurine [chemical structure shown]. All proteins of sea creatures contain large amounts of taurine, and also large amounts of glycine [chemical structure shown].
Crab protein contains more taurine and glycine than fish, but the best source of taurine and glycine is shellfish meat.
Taurine and glycine are not essential for adults: our bodies can make them from the amino acids we ingest from our food.
The figure below shows the amount [in g per kg] of taurine and glycine in the five types of food that the Scandinavians fed their mice.
To cut a long story short: the more glycine and taurine the mice ingested, the less body fat they built up. The mice that got their protein from shellfish became slimmer, despite their fat- and sugar-rich diet, and did not lose lean body mass either.
So glycine and taurine have a slimming effect. But how does this work? The researchers don't know. A shellfish diet reduced appetite a little, but they were not able to work out whether glycine and taurine reduce the amount of energy derived from food, or whether they increase calorie burning.
The study was funded by the Norwegian government, the shellfish sector and Novo Nordisk.
Amino Acids. 2014 Jul;46(7):1659-71.
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