Troops/ up level

Any ideas to raise the level of the troops? I have 4 * to 14 but now 10 troops raise me only 150 points and it costs me 800,000 food. It is effective to raise a 1 * troop with 10 1 * troops since it only costs 10,000 faith food and then feed it to the 4 * - 14 Troop?
Does anyone use another formula? I have more than 200 troops of each color of 1 *