It's best to understand the the concept of stress and recovery. Stress includes activities such as training (Starting Strength in your case) as well as emotional and pressure related sources. Recovery is the process of adapting to deal with that stress. It includes both rest and nutrition.
- You can't maintain linear growth forever. The Starting Strength book acknowledges that, and gives you instructions for what to do.
- Lack of food can cause insufficient recovery
- So can lack of sleep
- As well as insufficient rest between sets
It's important to understand who Starting Strength is addressed to: beginners. A beginner is at the one time stage in their training career where they can make improvements just about every time they step in the gym. It's a wonderful time. Eventually, as the weights get heavier, the stress from training becomes so much that it takes you a week to recover and adapt. That's when you've hit intermediate stages, and you need to look for a program that supports weekly growth.
The most common lift to struggle with first is the overhead press (AKA standing military press, or simply the press). It's using the weakest muscles most of us have, but it's an absolutely great exercise to help build a strong shoulder girdle and prevent rotator cuff injuries on bench press. According to the SS book, you simply repeat the weight next time. If you stall three times, then you deload 10%.
Things to look at when you hit the wall:
- Did I sleep well? Most muscle growth occurs while you are sleeping.
- How much rest between sets did I have? You may have to increase the time to compensate for the volume.
- How much did I eat? The basic principle is simple, but there is a bit more to it than just that.
Some people can lift in a fasted state, and their body is used to it. They compensate later on in the day to get their required nutrition. Rip's dietary advice to beginners is simple: eat big, eat lots of protein, and don't worry about your stinkin' abs. If you are predisposed to gain weight, that may not work for you. If you've always been a skinny guy, that's definitely the advice you need.
Very common recommendations for the food you need is:
- 1g protein per pound lean body weight minimum, most commonly suggested is 1g per pound total body weight. (Lean is without fat, total is what the scale says)
- Remainder of calories from both carbs and fat
- Maintenance calories are roughly 15 Calories per pound total body weight. (Note: this is a ballpark figure that will always need adjustment).
In short, to stay the same weight eat the maintenance calories. To gain weight, eat 20% more than maintenance. To lose weight, eat 20% less than maintenance. Even if you keep the maintenance calories, and you currently have a lot of fat, the act of training will help build muscle and the body will compensate by keeping less fat around. It's not 1-to-1, but you get the general idea.