Weight Gainer
A high-calorie supplement combining protein (usually whey) and carbohydrates (maltodextrin, oats and the like) in high ratios, formulated to deliver 600-1,200 kcal per serving for people who cannot reach caloric targets through food alone. The studies we hold on gaining weight answer different questions. One compared larger and smaller weight-gain protocols in elite athletes and found greater fat gain in the group eating more. Another varied protein intake in resistance-trained people and found no significant change in body weight, fat mass or lean mass. They differ in population, intervention, duration and measurement, and together they cannot establish whether outcomes depend on the source of the calories. Both are small single studies, and both assume total intake and its composition are being managed.
An ingredient with growing research
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Effects reported in research
What the product does is make calories easier to consume. A 600-1,200 kcal serving is designed to close the gap for people who cannot reach their target through food alone. We hold no study testing that use directly.
For the protein component, a meta-analysis found that adding protein supplementation to resistance training of six weeks or more increased 1RM strength by 2.49 kg, lean mass by 0.30 kg and muscle fibre cross-sectional area by 310 µm² (protein-intake-muscle-meta). Beyond a total protein intake of 1.62 g per kg of body weight per day, however, no further gain in lean mass was seen.
In the same analysis the benefit was larger in trained individuals (+0.75 kg) and diminished with age (-0.01 kg of lean mass per year). It covers healthy adults in RCTs with at least six weeks of resistance training.
On glycogen replenishment or readiness from the carbohydrate component, we can point to no source. It is a commonly repeated explanation, not something the three studies here tested.
Dosage & timing
- Typically 600-1,200 kcal per serving depending on the product — note first how much denser that is than a standard protein powder (20-40 g per serving).
- On how fast to gain, Garthe et al.
- (2013) compared 39 elite athletes (mean age 19, over 8-12 weeks) assigned to nutritional counselling or ad libitum intake. Total energy intake was 3,585 kcal/day versus 2,964 kcal/day — these are total intakes, not surpluses above maintenance.
- Body weight rose more in the counselling group (+3.9% vs +1.5%), but the gain in lean mass did not differ between groups — only fat mass did (+15% vs +3%).
- The authors conclude that excess energy in a weight-gain protocol should be considered carefully because of undesirable increases in body fat.
- A modest surplus of around 200-300 kcal per day ('lean bulk') is often cited as a way to limit fat gain, though we hold no trial testing that specific figure.
- Nor do we hold a trial comparing timing (post-workout versus between meals).
Cautions
- •The two studies we hold on gaining weight answer different questions. Garthe et al.
- •(2013), in 39 elite athletes over 8-12 weeks, compared a larger and a smaller weight-gain protocol and found greater fat gain in the group eating more (3,585 kcal/day; +15% vs +3%).
- •Antonio et al.
- •(2014), in 30 resistance-trained people over eight weeks, varied protein intake and found no significant change in body weight, fat mass or lean mass even at 4.4 g of protein per kg of body weight per day. They differ in population, intervention, duration and how intake was measured. Neither compared carbohydrate-derived with protein-derived surpluses, so whether outcomes depend on the calorie source cannot be determined from them. Antonio's result cannot be used to argue that a carbohydrate-heavy weight gainer will not add fat, and that trial has its own limits: 30 participants and self-reported intake. In Garthe et al. (2013), the group eating more saw their 40 m sprint time significantly worsen. Gaining weight can itself work against athletic performance.
- •Because one serving can supply several hundred to over 1,000 kcal, managing total daily calories is a precondition.
- •Products heavy in maltodextrin are held to raise blood glucose sharply, so anyone managing blood sugar should check the ingredient list.
- •The large serving may cause digestive discomfort or bloating.
- •Those with lactose intolerance should be cautious with whey-based products and consider a WPI-based alternative.
- •This information is for educational purposes only and is not intended to diagnose or treat any condition.
Supporting research
Protein supplementation augments resistance-training-induced gains in muscle mass and strength (meta-analysis)
British Journal of Sports Medicine, 2018
A meta-analysis pooling 49 randomised controlled trials (1,863 participants) in healthy adults. Adding protein supplementation to resistance training of at least six weeks significantly increased one-repetition-maximum strength (+2.49 kg), fat-free mass (+0.30 kg) and muscle fibre cross-sectional area (+310 µm²). The effect of supplementation diminished with increasing age and was larger in resistance-trained individuals. Beyond a total protein intake of 1.62 g/kg/day, no further gains in fat-free mass were observed.
Magnitude of Energy Surplus and Body Composition in Elite Athletes: An RCT
European Journal of Sport Science, 2013
In 39 elite athletes (mean age 19) randomized to a planned nutritional counseling group (~3585 kcal) or an ad libitum group (2964 kcal) over 8–12 weeks, gains in lean body mass did not differ between groups, while a larger surplus produced a larger increase in fat mass.
High-Protein Overfeeding and Body Composition in Trained Individuals: An 8-Week RCT
Journal of the International Society of Sports Nutrition, 2014
In 30 resistance-trained individuals (mean age 24), comparing a high-protein group (4.4 g/kg/day, 307 g/day) with a control group (1.8 g/kg, 138 g/day) over 8 weeks, there were no significant within- or between-group changes in body mass, fat mass, lean mass, or body fat percentage; the surplus of protein calories did not increase fat.
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