FormFlectWhat the evidence says.
And what FormFlect does about it.
Fitness is full of confident claims. Below are the ones that shape how FormFlect works, each graded against peer-reviewed research — including the popular claims we deliberately left out. Where the evidence is mixed, we say so.
Energy balance and counting
Energy balance itself is not in dispute. The useful part of the claim is about the tool: self-reported intake is under-recorded by 20–40% even in motivated people (Lichtman 1992; doubly-labelled-water studies), food labels may legally deviate by up to 20%, and adherence to logging collapses within weeks for most users. Structured tracking does beat no tracking in trials — but it is an unreliable, unpleasant proxy, not a wrong one.
Leptin falls and ghrelin rises in a deficit; appetite hormones remain shifted a year after weight loss (Sumithran 2011). Most dieters regain within 2–5 years.
Mostly true, but not in the way people mean: the large effect is a 200–400 kcal/day fall in non-exercise activity (NEAT) during a diet (Levine; Rosenbaum & Leibel). Adaptive thermogenesis beyond that is real but smaller.
Muscle, protein and rate of loss
Fat-free mass is the main determinant of resting energy expenditure, and its loss predicts post-diet overeating (Dulloo). Preserving it is the best-supported lever for keeping weight off.
Slower loss preserves lean mass better in athletes (Garthe 2011) and general populations; 0.5–1%/week is the consensus coaching range.
1.6–2.4 g/kg/day during a deficit preserves lean mass (Morton 2018 meta-analysis; Helms 2014 for lean individuals).
Resistance training in a deficit is the strongest protector of lean mass (Sardeli 2018); it improves glycaemic control comparably to aerobic work (Umpierre 2011). Contraction-driven glucose uptake is insulin-independent.
Exercise-only interventions produce modest loss (people compensate); but high activity is the strongest correlate of keeping weight off (National Weight Control Registry).
DXA sub-studies found ~39% of semaglutide weight loss was lean mass (which includes water, organ tissue and bone, not only muscle) — a proportion similar to fast diet-induced loss without resistance training. Older adults are at real risk of irreversible bone and muscle loss.
Carbohydrates, sugar and fat distribution
Controlled feeding studies show no fat-loss advantage for low-carb at matched calories (Hall 2017, 2021), and time-restricted eating works when it reduces intake — not otherwise (Liu, NEJM 2022).
Excess fructose in a calorie surplus raises liver fat via de novo lipogenesis (Schwarz 2015); isocaloric swaps show smaller effects. Fatty liver prevalence is roughly 30–38% of adults globally.
Spot reduction does not occur (Vispute 2011). Visceral fat does, however, go early in overall fat loss.
Sleep, stress and caffeine
One night of four hours’ sleep reduces insulin sensitivity by ~20–25% (Donga 2010); chronic short sleep raises hunger and intake, and sleep extension reduces intake (Tasali 2022).
Acute caffeine reduces insulin sensitivity in lab studies (Keijzers 2002), but habitual coffee consumption is associated with lower type-2 diabetes risk across 28 cohorts (Ding 2014), and tolerance develops. Caffeine 30–60 min before training improves performance.
The cortisol awakening response is normal physiology; no trial shows a benefit from delaying caffeine 90 minutes.
Robust in rodents. In humans there is no validated non-invasive marker and no dosing data; any energy deficit (and exercise) upregulates autophagy — fasting is not special for it.
Fuelling around training
Carbohydrate plus protein 30–90 min before resistance training improves performance and blunts the exercise cortisol rise and muscle-protein breakdown (Bird 2006; Tipton 2001; ISSN position stand, Kerksick 2017). Fasted training gives no fat-loss advantage (Schoenfeld 2014) and costs performance in longer sessions (Aird 2018). Close to the session, low fat and fibre digest better.
The post-exercise “anabolic window” is hours wide, and total daily protein matters more than timing (Aragon & Schoenfeld 2013). Protein, 20–40 g, is the part that matters (Morton 2018); rapid carbohydrate refuelling only matters if you train again within ~8 hours.
References
- Aird TP et al. (2018). Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: a systematic review and meta-analysis. Scand J Med Sci Sports 28(5):1476–93.
- Aragon AA, Schoenfeld BJ (2013). Nutrient timing revisited: is there a post-exercise anabolic window? J Int Soc Sports Nutr 10:5.
- Bird SP et al. (2006). Liquid carbohydrate/essential amino acid ingestion during a short-term bout of resistance exercise suppresses myofibrillar protein degradation. Metabolism 55(5):570–7.
- Ding M et al. (2014). Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and dose-response meta-analysis. Diabetes Care 37(2):569–86.
- Donga E et al. (2010). A single night of partial sleep deprivation induces insulin resistance in multiple metabolic pathways in healthy subjects. J Clin Endocrinol Metab 95(6):2963–8.
- Drake C et al. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med 9(11):1195–1200.
- Dulloo AG et al. (2015). How dieting makes the lean fatter: collateral fattening. Obes Rev 16(S1):25–35.
- Garthe I et al. (2011). Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab 21(2):97–104.
- Hall KD et al. (2021). Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum energy intake. Nat Med 27:344–53. Hall KD, Guo J (2017). Obesity energetics: body weight regulation and the effects of diet composition. Gastroenterology 152(7):1718–27.
- Helms ER et al. (2014). A systematic review of dietary protein during caloric restriction in resistance trained lean athletes. Int J Sport Nutr Exerc Metab 24(2):127–38.
- Keijzers GB et al. (2002). Caffeine can decrease insulin sensitivity in humans. Diabetes Care 25(2):364–9.
- Kerksick CM et al. (2017). ISSN position stand: nutrient timing. J Int Soc Sports Nutr 14:33.
- Lichtman SW et al. (1992). Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med 327:1893–8.
- Liu D et al. (2022). Calorie restriction with or without time-restricted eating in weight loss. N Engl J Med 386:1495–1504.
- Morton RW et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength. Br J Sports Med 52:376–84.
- Rosenbaum M, Leibel RL (2010). Adaptive thermogenesis in humans. Int J Obes 34:S47–55. Levine JA (2004). Non-exercise activity thermogenesis. Nutr Rev 62:S82–97.
- Sardeli AV et al. (2018). Resistance training prevents muscle loss induced by caloric restriction in obese elderly individuals: a systematic review and meta-analysis. Nutrients 10(4):423.
- Schoenfeld BJ et al. (2014). Body composition changes associated with fasted versus non-fasted aerobic exercise. J Int Soc Sports Nutr 11:54.
- Schwarz JM et al. (2015). Effect of a high-fructose weight-maintaining diet on lipogenesis and liver fat. J Clin Endocrinol Metab 100(6):2434–42.
- Sumithran P et al. (2011). Long-term persistence of hormonal adaptations to weight loss. N Engl J Med 365:1597–1604.
- Tasali E et al. (2022). Effect of sleep extension on objectively assessed energy intake among adults with overweight. JAMA Intern Med 182(4):365–74.
- Tipton KD et al. (2001). Timing of amino acid–carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Am J Physiol Endocrinol Metab 281:E197–206.
- Umpierre D et al. (2011). Physical activity advice only or structured exercise training and association with HbA1c levels in type 2 diabetes. JAMA 305(17):1790–9.
- Vispute SS et al. (2011). The effect of abdominal exercise on abdominal fat. J Strength Cond Res 25(9):2559–64.
- Wilding JPH et al. (2021). Once-weekly semaglutide in adults with overweight or obesity (STEP 1), incl. DXA substudy. N Engl J Med 384:989–1002.