People often fail to meet their strength due to a lack of planning in the dietary aspects of the training sphere.
Goals are not enough, they have to be associated to an action plan.
It is a myth that 21 days are necessary to change an habit, the scientific research points out that it takes at least 66 days for the average person to install an habit.
From experience, whether you want to gain muscle mass and strength, the first goal you should establish is how much protein you should eat in a day. For males, who aim at increasing muscle mass and strength gains, if you only train once a day, 2 g a kg should be more than enough (for women 1.2g /kg of bodyweight).
With Olympic level athletes in strength sports who train up to 5 times a day, that value can climb up to 3.3 g/kg in accumulation phases, where they at increasing the cross-section. However, athletes that reach those needs in protein are about as rare as lawyers who under bill their clients!
That total protein amount should be spread out over 5 to 6 intakes a day, including any peri-workout intake (during/post).
Of course the quality of the protein matters. You can compare 40 grams of baloney protein to 40 grams of bison protein.
My former protein suggestions were based on working years with my usual clientele : Olympians and pro-athletes. However, to be fair, 99% of the readership of this website actually only devotes 4 to 5 session a week to resistance training.
Keep in mind, that in order to grow you will need a minimum of 40% of your calories comer carbs in the diet. Higher intakes are indicated when one has great insulin sensitivity and has the training volume to validate it. Again for most of the readers, 40% is probably better.
There are three populations who in my experience need higher protein intakes (3.3-4.4 g/kg) :
1. insulin resistant morbidly obese, ultra-low carb. As their insulin sensitivity improves the protein will go down, being replaced by paleo carbs.
2. Athletes who are fully dedicated to developing hypertrophy/strength, however they have to train enough: more than 2 sessions a day. An extremely small percentage of the training population. For a lot of them, they actually finally recover once they move that up. Keep in mind that Ed Coan became one of the strongest men in history with a very limited workload, his protein intake being circa 2 g/kg. Individualization is key : not growing ? try more protein ; still not growing : cut back on protein increase carbs….
3. People from phenotypes that respond better to high protein i.e. Native Americans. Keep in mind that their expenditure is also much higher too.
Enjoy the path,
P.S. If you want a pretty review of the topic, please read my friend Paul Carter’s article