Many bodybuilding opinions exist in regards to achieving maximum muscle gains with the smallest possible body fat percentage, with weight lifters attempting to manipulate diet variables, including whether to consume food prior to sleep, in order to improve results. Some bodybuilders understand the value of a bedtime meal, but others avoid food prior to sleep, especially weight lifters who either quickly gain fat when aiming for muscle growth, or who are focusing specifically on fat loss, and wish to boost the rate of progress.

The theory is that food prior to sleep encourages fat gain, and although there is no inherent harm to body fat levels when consuming a late meal, because many diet routines are structured with an incorrect use of calories and carbohydrates, not to mention improper meal division, which can detract from metabolic rate, eating before sleep encourages fat increase for many, and some in the weight lifting world classify later eating as harmful towards body fat percentage.

The common mistake made is to either use excessive carbohydrates for a bedtime meal, or implement a food intake that circumvents the body's core requirements for muscle gain or maintenance, which then quickly will result in body fat increase, as energy expenditure during evening fast is less than at any other time. Yet, unlike certain flawed weight lifting trainers may suggest, a bodybuilder is in great need of calories during sleep, as this is when muscle gains occur at their greatest proportion. In fact, since the body has a lengthy uninterrupted rest to repair and grow lean muscle tissue, sufficient calories and protein must be present in order to maximize such results, which is why a bedtime meal becomes crucial. When nutrients are neglected prior to a lengthy rest period, although muscles wish to grow during such hours, they are unable to do so, and if an individual is consuming a lower calorie diet for fat reduction, many times muscle mass will even drop dramatically.

During fat loss periods, one of the most challenging obstacles for many weight lifters is muscle maintenance, and making dramatic modifications to a diet, whether it be reducing food intake below what is necessary for fat loss due to impatience, or dramatically restricting food later in the evening, will greatly increase the chance for lost muscle, which further suppresses metabolism, making future fat loss difficult. Unbeknownst to many, a properly structured bedtime meal can actually assist in the fat reduction process, as metabolism is stimulated due to a frequent meal structure, and withholding food for extended periods can cause the body to limit calorie burn. This can occur not only when decreasing the number of meals during daylight hours, but also by skipping a moderately sized feeding prior to sleep. This contradicts the notion that food before rest increases the chance of fat increase or slows fat reduction, but far too many who integrate bedtime meals are consuming a larger quantity of food than is necessary to properly fuel metabolism and maintain muscle mass, or are using excessive carbohydrates, as if the meal were preceding a weight lifting workout as opposed to a lengthy sleep session. A meal prior to sleep should be composed of mostly protein, as the body during rest is seeking primarily recovery and growth (by way of protein synthesis), but eradicating carbohydrates will cause the body to use protein for energy, which reduces available nutrients for muscle recuperation, and places metabolism at risk.

Certain weight lifters understand the importance of bedtime meals, and try to consume several during the evening, waking up once or twice for extra food, believing this will increase muscle building results, but such a technique is harmful to overall progress, as consuming one correctly designed bedtime meal is sufficient to promote muscle gains and proper metabolic function, while waking up for another one or two meals will disrupt proper sleep patterns, which are just as vital for muscle gains and proper metabolism as the meal itself. Waking up for extra food during time which should be devoted to rest prevents the body from utilizing calories properly, so for maximum muscle building and fat loss, aiming for a bedtime meal with controlled carb intake and ample protein once before a lengthy sleep session is the most effective technique to aim for.