Releases stored fat

The step where stored fat actually leaves the fat cell — triglyceride split into fatty acids and glycerol, and let out into the blood.

The cell's go-signal increases it.

The canonical cascade, stated identically by four independent groups. Verbatim: 'When catecholamines bind to these receptors, stimulatory Gs proteins activate adenylate cyclase, causing a rise in cAMP levels and elevated activity of cAMP-dependent protein kinase-A (PKA)... PKA-mediated phosphorylation of target proteins, including lipolytic enzymes and lipid droplet-associated proteins, induces an increased release of FAs and glycerol from adipose tissue up to 100-fold.' the same pathway brakes itself: 'Through the same PKB-dependent pathway beta-adrenergic receptor signaling, via cAMP and PI3K-alpha, is anti-lipolytic and inhibits its own stimulation of lipolysis by 50%'.

Lipolysis signal increases it.

PKA is the key that opens the droplet, and the mechanism is resolved to individual serines. 'Under basal (fed) conditions, perilipin 1A provides a protective barrier against lipolysis of stored triacylglycerols and binds CGI-58, a coactivator of ATGL. When CGI-58 is sequestered on the perilipin scaffold, it cannot interact with or activate ATGL.' On stimulation: 'The phosphorylation of three N-terminal serine residues of perilipin 1A facilitates the docking of PKA-phosphorylated hormone-sensitive lipase... The PKA-mediated phosphorylation of two carboxyl-terminal serine residues facilitates the release of CGI-58 from perilipin 1A, enabling interaction of CGI-58 with ATGL, in turn activating the lipase' (PMC4274058). ATGL is 'the rate-limiting lipase in lipolysis'. PMC4274058

Beta-3 receptor signaling increases it.

PMC1909425 — A species caveat that must travel with this edge. Verbatim: 'Mouse adipocytes express three subtypes of beta-adrenergic receptors: beta1-AR, beta2-AR, and beta3-AR. In human adipose tissue, only BETA1 and BETA2 receptors induce lipolysis' (j Lipid Res, ATGL and the lipolytic catabolism of cellular fat stores). ⇒ beta-3 is the rodent lipolysis receptor. The edge is drawn because the beta-adrenergic route to lipolysis is not in doubt, but any claim resting on beta-3 specifically is a mouse claim until shown otherwise in people. PMC1909425

Alertness chemical increases it.

10.1017/s0029665109990279 — 'In adipose tissue, the most potent stimulatory signals are catecholamines acting on beta-adrenergic receptors.' And the same molecule works both ways: 'The neurotransmitter, noradrenaline, and the hormone, adrenaline, regulate lipolysis through lipolytic beta-adrenoceptors and antilipolytic ALPHA2-adrenoceptors... AR-dependent lipolysis is dictated by the combined effects of pro-lipolytic beta-AR and anti-lipolytic alpha2-AR.' and the disease finding: 'Impairment in PKA-stimulated lipolysis observed in obesity is thought to result from accentuated stimulation of ALPHA2-AR.'. doi 10.1017/s0029665109990279

Insulin sensitivity reduces it.

The brake, and it is fully explained rather than assumed. 'The anti-lipolytic effect of insulin can be fully explained by protein kinase b (pkb/Akt)-dependent activation of the phosphodiesterase PDE3B' — insulin does not block the switch, it destroys the messenger. 'Insulin favors cAMP degradation through activation of protein kinase B and phosphodiesterase 3B activity.' The dose-response is not linear: 'The dose-response of lipolysis is bell-shaped, such that insulin is anti-lipolytic at low concentrations, but at higher concentrations of insulin lipolysis was increasingly rest[ored]'. PMC6792037

Fasting response increases it.

10.1186/s40842-022-00137-y — 'The key process in fat catabolism and the provision of energy substrate during times of nutrient deprivation (fasting) or enhanced energy demand (e.g., exercise) is the hydrolytic cleavage of stored TG, the generation of FAs and glycerol, and their release from adipocytes' (J Lipid Res). Fasting is the physiological input state this entire pathway exists to serve. doi 10.1186/s40842-022-00137-y

Heart-derived pressure hormone increases it.

10.1017/s0029665109990279 — a second, fully independent trigger — different messenger, different kinase, same targets. 'Natriuretic peptides promote cGMP accumulation and PKG activation via type A receptor. PKA and PKG phosphorylate hormone-sensitive lipase (HSL) and perilipin A (PLINA)' (Proc Nutr Soc). And on division of labor between the lipases: 'Hormone-sensitive lipase appears as the major lipase for catecholamine and natriuretic peptide-stimulated lipolysis whereas adipose triglyceride lipase mediates the hydrolysis of triglycerides during basal lipolysis.' These are cardiac hormones. doi 10.1017/s0029665109990279

Energy sensing reduces it.

AMPK is a brake on lipolysis. Verbatim, from a review devoted to the molecular brakes of lipolysis: 'AMPK is activated in adipocytes during lipolysis. Upon activation, AMPK induces the inhibitory phosphorylation (Ser565) of HSL to impede active Ser563 phosphorylation by PKA, thereby inhibiting PKA-mediated activation of HSL and lipolysis' (doi 10.3389/fphys.2022.826314). It is a negative feedback loop, not a trigger: 'The activation of AMPK in adipocytes by lipolytic agents that increase intracellular cAMP level appears to be secondary to an increase in the AMP:ATP ratio that accompanies lipolysis' — and specifically 'AMPK is activated as a consequence of constitutively ongoing reesterification that consumes significant amounts of cellular ATP and generates AMP'. So the futile cycle itself switches on the brake. AMPK remains a legitimate activator of fatty-acid oxidation; it is on the disposal side, not the release side. The contradiction is now resolved, and the sign survives — with a human caveat that matters more than the sign. AMPK acts on two different enzymes in opposite directions: stimulatory on ATGL at Ser406 (the basal arm) and inhibitory on HSL at Ser565 (the stimulated arm). The knockout settles the NET: 'These mice also show defective phosphorylation of HSL at S565, with higher phosphorylation at PKA sites of S563 and S660, increasing its hydrolase activity and isoproterenol-stimulated lipolysis. With higher overall adipose lipolysis, both models of AMPK-ASKO ARE lean, having smaller adipocytes with lower TAG and higher intracellular free FA levels' (PMC (Kim et al., AMPK-ASKO)). ⇒ deleting AMPK makes the animal leaner, so the NET effect of AMPK on total lipolysis is inhibitory and the inh sign stands. But the human evidence does not reproduce it. A study titled 'AMPK activation by A-769662 and 991 does not affect catecholamine-induced lipolysis in human adipocytes' found that in primary human adipocytes the activator '991 also resulted in a significant increase in the phosphorylation of HSL at Ser660' — the activating site — 'although lipolysis was not altered' (doi 10.1152/ajpendo.00110.2018). ⇒ in people, AMPK activation hits the brake and the accelerator at once and NET release does not move. The edge is rodent-true and human-null, and this blend is for people. doi 10.3389/fphys.2022.826314

Blood flow to fat tissue increases it.

The causal proof that transport, not the enzymes, can be the limiting step. In perfused adipose tissue with lipolysis chemically stimulated, 'The supply of free fatty acid (ffa) carrier to the tissue was varied either by variations in the rate of blood flow or by changes in the albumin concentration of the perfusing blood at constant flow rate. The net production of ffa from the tissue was found to depend on the supply of carrier over a range from 0.1-12 micromoles of albumin x 100 g tissue-1 x min-1... The changes in ffa production appeared to be due to varying degrees of reesterification rather than changes in the rate of lipolysis' (PMID 7195565). The physiological framing: 'Neither TG nor NEFA are soluble to any extent in water, and their transport to and out of the tissue requires specialized transport mechanisms and adequate blood flow.' The perfusion experiment is canine tissue. PMID 7195565

Fat re-storage reduces it.

Net output is release minus what goes back, and what goes back is not small. 'It is believed that the primary factors determining the extent of reesterification within the adipocyte is the intracellular FFAs buffering via FABPs, the ability of plasma to carry away released ffa (i.e., blood flow and adequate albumin binding sites), and the availability of glucose to produce glycerol 3-phosphate for reesterification' (pmc8907745). This edge is drawn as inhibitory on net release, not on the hydrolysis reaction itself.

Fat-burning hormone reduces it.

Adiponectin, an adipokine, is a brake on lipolysis. 'Adiponectin has been shown to inhibit lipolysis by suppressing PKA-mediated HSL activation. In addition, adiponectin reduces the amount of PKA RII-alpha, the regulatory subunit of PKA, by impairing its protein stability. Overexpression of RII-alpha abolishes the inhibitory effects of adiponectin on lipolysis. Consistently, adiponectin-knockout mice and their primary adipocytes exhibit an increased lipolysis.' The complication is real and stated: 'adipose tissue expression and circulating concentrations of adiponectin are decreased in both overweight and obesity, thereby implying a plausibly decreased anti-lipolytic effect' — so in overweight and obesity the brake is already partly off. doi 10.3389/fphys.2022.826314

Fat-releasing enzyme (ATGL) increases it.

'ATGL, considered the rate-limiting enzyme, catalyzes the first step, hydrolyzing TGs to diglycerides, which in turn are degraded by HSL into monoglycerides, with the release of a FFA in each step' (doi 10.3389/fphys.2022.826314). And on division of labor: 'adipose triglyceride lipase mediates the hydrolysis of triglycerides during basal lipolysis'. doi 10.3389/fphys.2022.826314

Fat-releasing enzyme (HSL) increases it.

'hormone-sensitive lipase appears as the major lipase for catecholamine and natriuretic peptide-stimulated lipolysis whereas adipose triglyceride lipase mediates the hydrolysis of triglycerides during basal lipolysis' (doi 10.1016/j.biopha.2006.02.005). The human consequence of losing it is recorded: 'HSL deficiency in human patients results in impaired adipocyte development and high plasma lipid levels which eventually leads to ectopic lipid accumulation and insulin resistance' (doi 10.3389/fphys.2022.826314). My node card called this 'the second cut'. That is incomplete. 'ATGL and HSL both have the capacity to initiate TG degradation by cleaving the first ester bond, but HSL is unique in its capacity to break down the second ester bond, converting diglycerides to monoglycerides' (doi 10.1074/jbc.M109.008631 [PMC2709346]). ⇒ HSL can do both cuts; it is the only one that can do the second. And a defect in the target population that changes the product's premise: 'It is well known that expression of HSL is markedly decreased in subcutaneous adipocytes and differentiated adipocytes from obese subjects. This suggests that, at least in adipose tissue, a decreased HSL expression is a primary defect in obesity' (PMC2453623). The enzyme itself is depleted in the people this product is for — which is why the drivers that raise HSL mRNA and protein, rather than only phosphorylating what is there, matter more than they first appeared. doi 10.1016/j.biopha.2006.02.005 · PMC2709346

Final fat cut increases it.

'Finally, mgl completes the process through the hydrolyzation of the last ester bond in monoglycerides, generating one last ffa and a glycerol backbone' (doi 10.3389/fphys.2022.826314). And the reason it is not a target: 'Adipose TAG lipase (ATGL) and MONOACYLGLYCEROL lipase (MGL) ARE not thought to be directly hormonally-regulated' (Proc Nutr Soc). Included for completeness of the cascade, not as a lever. Independently confirmed as not a lever: 'The non-rate-limiting monoglyceride lipase completes lipolysis by cleaving the last ester bond from a monoglyceride molecule, leading to glycerol release'. doi 10.3389/fphys.2022.826314

It reduces Subcutaneous fat.

Mice lacking adipose triglyceride lipase could not mobilise stored triacylglycerol and consequently carried increased adipose mass with triacylglycerol deposition in multiple tissues, showing that lipolysis is the step that depletes stored fat. doi 10.1126/science.1123965 · PMID 16675698

It increases Fat burning.

10.7554/eLife.31132 — 10.3390/biom10121699 — the reason a release lane only means something alongside a burning lane. Lipolysis produces 'the generation of FAs and glycerol, and their release from adipocytes' — fatty acids in the blood. What happens next is a separate question: they are oxidized, re-esterified, or delivered to other tissue. This is the limit of any 'fat release' claim. doi 10.7554/eLife.31132

It reduces Supports weight management.

10.1371/journal.pone.0037794 — Lipolysis is the mobilization step of fat mass: 'the hydrolytic cleavage of stored TG, the generation of FAs and glycerol, and their release from adipocytes' is by definition the withdrawal of stored energy. Mobilization is not loss. Released fatty acids that are not oxidized are re-esterified back into the droplet; this edge is drawn on the direction of the step, not on a demonstrated weight outcome. doi 10.1371/journal.pone.0037794

It increases Fat re-storage.

The sentence that caps this entire product category: 'the absolute rates of reesterification of FFAs are reported to increase proportionally with the rate of lipolysis' (pmc8907745, citing Reshef 1970 and Brooks 1982). Pushing release harder recruits more putting-back. That is why a release lane taken alone has a ceiling built into its own physiology, and why this blend carries a disposal lane and a perfusion lane rather than release alone.

It increases Fat transport protein.

The sponge is also the courier, and both directions are on the record. 'lipolysis-derived fatty acids are shuttled by fatty acid-binding proteins (FABPs) to the nucleus, where they are necessary for proper PPAR signaling' (doi 10.3389/fphys.2022.826314). And systemically: 'The circulating lipid chaperone called A-FABP has been reported to facilitate ffa import from wat into bat.' ⇒ removing it would cost the delivery system as well as the buffer. A structural confirmation of the dual role: HSL's 'N-terminal domain binds the fatty acid binding protein 4 (FABP4), and participates in HSL dimer formation' (Cell Metab, 'Nuclear hormone-sensitive lipase regulates adipose tissue mass and adipocyte metabolism'). The buffer protein is physically bound to the lipase itself. doi 10.3389/fphys.2022.826314

It increases Activated fatty acids.

'lipolysis derived FFAs need to be activated to metabolizable lc-CoAs via the long-chain acyl coenzyme A synthetase for further metabolization such as beta-oxidation, synthesis of complex lipids, or protein acylation' (doi 10.3389/fphys.2022.826314). ⇒ the fat you release becomes the molecule that stops further release, unless burned or carried away. doi 10.3389/fphys.2022.826314

It increases Fatty acid receptor.

10.1016/j.molmet.2020.101103 — Long-chain fatty acids are the direct product of fat release, and they are named as ligands of this receptor (doi 10.3389/fphys.2022.826314). ⇒ the product signals from outside the cell to stop its own production — a parallel to the intracellular acyl-CoA route, by a completely different mechanism. doi 10.1016/j.molmet.2020.101103

It increases Where glycerol goes.

10.4103/bbrj.bbrj_14_20 — Nbk560564 — the futile cycle has a second, whole-body arm — and it was the german reference that named it. 'Das in der Lipolyze entstandene Glycerin wird ebenfalls von der Leber abgebaut und zur GLUCONEOGENESE oder FETTSÄURESYNTHESE herangezogen' = the glycerol produced by lipolysis is broken down by the liver and used for gluconeogenesis OR fatty-acid synthesis (flexikon.doccheck.com/de/Lipolyze (deutsch)). ⇒ the re-esterification node covers what is recaptured inside the fat cell. This is what is recaptured after it has left: the glycerol travels to the liver and can be rebuilt into fatty acids there. The consequence for every glycerol measurement in this formula: glycerol appearing in blood proves fat left the cell. It does not prove fat left the body. Almost every driver here is graded on glycerol release, and that is the honest ceiling on what those numbers mean. doi 10.4103/bbrj.bbrj_14_20

It increases Ketone production.

10.1186/s13054-019-2506-6 — The other disposal route, and the one that actually removes fat from the body. 'Die aus der enzymatischen Spaltung entstandenen Fettsäuren werden in das Blut abgegeben. Sie können von der Muskulatur zur beta-oxidation oder von der Leber zur KETOGENESE aufgenommen und verstoffwechselt werden' = the fatty acids from lipolysis enter the blood and can be taken up by muscle for beta-oxidation or by the liver for ketogenesis (DocCheck Flexikon — Lipolyze (deutsch)). ⇒ released fat has exactly two honest exits — burned in muscle, OR converted to ketones in the liver. Everything else is recapture. A release agent with neither exit open is moving fat around, not removing it. doi 10.1186/s13054-019-2506-6

Lipolytic (Stored-Fat Mobilization) →

Purge (Intestinal Clearance) →

B3AR Activator (Catecholamine Response Restored) →